Monday

May 25, 2015

May 25, 2015

Total # Posts: 1,849

**math**

Use the pythagorean theorem: c^2 = a^2 + b^2 where c = hypotenuse a = one leg b = the other leg In the problem, a = 9 b = 12 Now solve for c using the equation above.
*October 31, 2013*

**math**

If a point is reflected over the y-axis, the y-coordinate of the new point is equal to the original, while the x-coordinate is the negative of the original. Therefore, if the point is (8, -10), the reflected point is at (-8, -10). Hope this helps :3
*October 31, 2013*

**Math**

The conversion is 1 yard = 3 feet. Thus, 1 yd^3 = 3^3 ft^3 or 27 ft^3 If there are 3 yards, 3 yd^3 = 3 * 27 ft^3 = 81 ft^3 You're correct. :)
*October 31, 2013*

**math**

Recall that are of triangle is just A = (1/2)bh where b = base h = height It was said that the base is half of the height, or b = (1/2)h. Substituting to the formula, A = (1/2)(1/2)h*h 121 = (1/4)*h^2 484 = h^2 h = 22 m Solving for the base, b = (1/2)*22 = 11 m Hope this helps...
*October 31, 2013*

**Substituion MATH**

It's wrong, I don't know how you checked but x = 32 and y = 6 actually doesn't satisfy either given equation. Anyway, okay let's do #2. -1/2x - 1/4y = 3 1/3x + 1/6y = 2 To deal with fractions, it's easier if you first make them whole numbers by multiplying ...
*October 31, 2013*

**Substituion MATH**

#1. -x + 10y = 60 -4x + 16y = 32 If we need to use the substitution method, we choose an equation and let one of the variable in terms of the other. Then we substitute it to the other equation. Here, let's choose the first equation. -x + 10y = 60 Then let's choose the ...
*October 31, 2013*

**math (please help)**

#1. Note that horizontal line has a zero slope, and in the form y = c, where c is a any real number. Therefore, if it passes thru the point (-8,8), the equation must be y = 8. #2. If we are given the two points on the line, we first get the slope using the formula m = (y2 - y1...
*October 31, 2013*

**math**

Let A = cost of one apple Let P = cost of one ponkan According to the first statement, 4A + 2P = 53 According to the second statement, 2A + 4P = 75 Now we're looking for 6A + 6P (because half a dozen is equal to six). Notice that if we add the equations, we'll get 6A...
*October 31, 2013*

**8th grade chemistry**

C. NaHCO3 It actually contains 6 atoms. :3
*October 31, 2013*

**Geometry**

#1. I believe there should be a given figure... #2 & #3. We need the choices...
*October 29, 2013*

**Calculus**

Get the derivative with respect to x: f(x) = -2x^3 + 33x^2 - 108x + 2 f'(x) = -6x^2 + 66x - 108 Let f'(x) = 0 and get the values of x: 0 = -6x^2 + 66x - 108 0 = x^2 - 11x + 18 0 = (x - 2)(x - 9) x = 2 and x = 9 Therefore, A = 2 and B = 9. At (-Inf , 2] : decreasing (...
*October 29, 2013*

**chemistry**

The reaction is P4 + O2 -> P2O5 Balancing, P4 + 5 O2 -> 2 P2O5
*October 29, 2013*

**Physics**

*lol sorry, in the last calculation that should be 5.125 * 10^-11 * 6.022 * 10^23 but the answer is still the same. :)
*October 29, 2013*

**Physics**

Since the gas is ideal, we can use the Ideal Gas Law: PV = nRT where P = pressure in atm V = volume in L n = number of moles of air R = universal gas constant = 0.0821 L-atm/mol-K T = temperature in K We first convert the given in the appropriate units: V = 19.4 cm^3 cm^3 is ...
*October 29, 2013*

**Ap chemistry**

We first write the balanced chemical reaction: 4 Mn + 3 O2 -> 2 Mn2O3 ; ΔH = -962.3 kJ/mol Mn2O3 We then get the number of moles Mn by dividing the given mass by molar mass of Mn. The molar mass of Mn is 54.94 g/mol (get a periodic table and search for it). 6.4 / 54.94...
*October 29, 2013*

**algebra**

You forgot to type the function...
*October 29, 2013*

**Gen Chem 2**

f (# of equivalents) is equal to number of ionizable H+ (in acid-base titration), though it has also other meaning, for instance, in electrochemistry. Here, f = 2 because H2SO3 has 2 H+.
*October 29, 2013*

**GCC**

In the activity series, Na is more reactive than Mg, thus it can displace Mg: Mg(NO3)2 + Na -> NaNO3 + Mg Balancing the reaction, Mg(NO3)2 + 2Na -> 2NaNO3 + Mg Hope this helps :)
*October 29, 2013*

**Maths**

Your solution and answer are actually both correct. :)
*October 28, 2013*

**chemistry**

lol I think you forgot to put the arrow symbol somewhere in those reactions. But it can still be answered. The answer is Ba(NO3)2(aq) + Na2CrO4(aq) -> BaCrO4(s) + 2NaNO3(aq) This is just a double displacement reaction. And looking at the charge of each element involved (in ...
*October 27, 2013*

**Math**

No, you don't have to. 30 / 3 = 10 Here, 10 is positive because both 30 and 3 are positive. 30 / -3 = -10 While here, one of them is negative so the answer must also be negative. *Note that if however, both 30 and 3 are negative, the answer is positive.
*October 27, 2013*

**Math**

Your solution and answer are actually correct. :) Let's do the checking part: Y = 4Y + 30 if Y = -10, -10 = -10(4) + 30 -10 = -40 + 30 -10 = -10 Since both sides of the equation are equal, then Y is indeed equal to -10. Hope this helps :3
*October 27, 2013*

**Pre-Calculus**

So we must transform tan(A) + cot(A) into csc(A)*sec(A). tan(A) + cot(A) Note that cot(A) is equal to 1/tan(A). Substituting, = tan(A) + 1/tan(A) = (tan^2 (A) + 1) / tan(A) Recall the pythagorean identity: tan^2 (A) + 1 = sec^2 (A). Also tan(A) = sin(A)/cos(A) and sec(A) = 1/...
*October 27, 2013*

**Geometry**

I believe there should be a given figure in the problem...?
*October 27, 2013*

**Math**

If you mean, 5^(2-x) = 7^(5x + 7) Then, we take the ln of both sides (2-x)*ln(5) = (5x + 7)*ln(7) 1.609*(2-x) = 1.946*(5x+7) Solving for x, x = -0.9174 Hope this helps :3
*October 26, 2013*

**Alg 2**

y varies directly with x: y = kx where k is some constant. To find this k, substitute the given x and y: 64 = k(16) k = 64/16 k = 4 To find x, substitute y = 288 and k = 4: 288 = 4x Now solve for x. Hope this helps :3
*October 25, 2013*

**college algebra**

Go to wolframalpha. com and type the given.
*October 24, 2013*

**Maths**

If you draw this one, you would actually form a right triangle, where the hypotenuse is the length of the ladder (15 ft), and one of the legs is the distance from the wall to the bottom end of ladder (9 ft). What we're looking for is also the length of the other leg. ...
*October 24, 2013*

**math**

Yes, it's correct.
*October 24, 2013*

**cal**

Recall the chain rule. If two expressions which are functions of x are multiplied, we do the following: h(x) = f(x)*g(x) h'(x) = f'(x)*g(x) + f(x)*g'(x) As we can see, the derivative of h(x) is the derivative of f(x) multiplied by the original g(x), plus the ...
*October 24, 2013*

**cal**

If you mean f(x) = x^8√(5-3x), then f'(x) = (8x^7)*√(5-3x) + (-3/2)*(x^8) / √(5-3x)
*October 24, 2013*

**Algebra**

Yes, they are all equivalent. To prove, assume a real value of x, for instance, x = 2. Then we substitute this value to each expression. The answers must be equal since the expressions are equivalent: 1800(x+20) ; x=2 1800(2+20) = 1800(22) = 39,600 1800x + 20(1800) ; x=2 1800(...
*October 24, 2013*

**math**

(a) To get the maximum profit, we differentiate the given function with respect to u. And then equate everything to zero (because at maximum, the slope is zero): P = -0.032u^2 + 46u - 3000 dP/du = -0.064u + 46 0 = -0.064u + 46 0.064u = 46 u = 718.75 (this is the number of ...
*October 24, 2013*

**math-correction**

*lol, sorry it shouldn't be dA/dt, rather dA/dW = 62.5 - 2W but it won't affect the answer anyway. (it's just that you might wonder where the variable t came from) ^^;
*October 22, 2013*

**math**

Since there is additional 15 m which is part of one side of the wall, we can say that the total fencing material is 110 + 15 = 125 m Recall that perimeter of rectangle is just P = 2(L + W) where L is the length and W is width. Substituting, 125 = 2(L + W) 62.5 = L + W, or L = ...
*October 22, 2013*

**math**

Let A = number of Aaron's cards Let B = number of Benga's cards From the first statement, the total number of their cards is 976, so A + B = 976 From the second statement, B = 7A Thus we can say, A + 7A = 976 8A = 976 A = 122 B = 854 Now, let x = number of cards that ...
*October 22, 2013*

**chemistry**

First separate the reaction into reduction and oxidation reactions. Then add the right number of electrons to balance the charges. Reduction: Mn(2+) -> Mn(5+) Mn(2+) -> Mn(5+) + 3e- Oxidation: Sn(2+) -> Sn Sn(2+) + 2e- -> Sn And then balance both reactions such ...
*October 21, 2013*

**Algebra**

Let n be the number (n / -9) + 10 = 11 Solving, -n / 9 = 11 - 10 -n / 9 = 1 n = -9 Hope this helps :3
*October 21, 2013*

**Math**

Is that division, like this, (2^4 * 3^9) / (3^5 * 2^7) ? If it is, then, yep, the answer is 2^-3 * 3^4.
*October 21, 2013*

**Chemistry-correction**

*sorry, my conversion of 2.5 kg to g is wrong. The equation should be Q = (2500 / 200.6)*(28.0)*(-6 -(-20))
*October 21, 2013*

**Chemistry**

Through out the temperature range, Hg remains as liquid. Recall that heat released or absorbed is given by Q = m*c*(T2 - T1) where m = mass c = specific heat T = temperature Note that molar mass of Hg is 200.6 g/mol. Substituting, Q = (250000 / 200.6)*(28.0)*(-6 -(-20)) Q = ? ...
*October 21, 2013*

**math**

Slope intercept form is y = mx + b. We just convert the given equation in this form: 2x + y = -7 y = -2x - 7
*October 21, 2013*

**college algebra**

sqrt(x) + 7 Domain is the set of all possible values of x. Here, note that x is inside a squareroot radical sign and therefore cannot be less than zero. Thus domain is all real numbers greater than or equal to zero. In symbols: [0 , +infinity) Hope this helps :)
*October 21, 2013*

**math**

x^2 + x - 20 = (x + 5)(x - 4)
*October 21, 2013*

**math**

x^2 + 9x +18 = (x + 3)(x + 6)
*October 21, 2013*

**college physics**

a. Of course, one way for athlete 1 to overtake athlete 2 is for him to accelerate (that is, if v2 > v1). But since the given are constant speeds, surely v2 MUST BE LESS THAN v1 in order for athlete 1 to overtake athlete 2, WITHOUT accelerating. b. Recall that the distance ...
*October 21, 2013*

**Science help! URGENT. Check answers**

1. Nope. If the net forces are zero, it means that the object is at an equilibrium state (may be static of dynamic), and thus implies the forces cancel or balance each other out. 2. It's actually air resistance. I suggest you read about Aristotle's and Galileo's ...
*October 21, 2013*

**chemistry**

It's an exothermic reaction, since heat is released.
*October 21, 2013*

**MATHS**

By trial and error: Perry's age = 73 Laura's age = 37 Difference of their ages = 36 years Checking: 73-1 = 2(37-1) 72 = 2(36) 72 = 72
*October 21, 2013*

**Pre-Calc**

f(x) = (x^5+3x^3+5x) / (4x^4+2x^2) The only common factor of numerator and denominator is x, but it isn't really necessary to cancel it. i. Vertical Asymptote To get this, we get the limit of x, as f(x) approaches infinity. lim x as f(x)->infinity Or easier way is to ...
*October 18, 2013*

**Math**

1. Yep 2. Yep 3. Yep
*October 18, 2013*

**math**

a. As the problem hinted, Let x = number of weeks Let y = dollars saved For the first equation: you have initially $50, and $10 is added each week. Therefore, at the end of x weeks, the total amount of money you'll have is, y = 50 + 10x For the second equation: same ...
*October 18, 2013*

**Math**

Yes, x can be -13 or 13.
*October 18, 2013*

**maths**

What is the operation? Are we to divide them? And, please clarify the 13^1/2x^2, if it's 13^(1/2 x^2) or 13^(1/(2x^2)).
*October 18, 2013*

**math**

Let x = Mary's age The condition given, in symbols, is x + 10 = 2x - 5 Solving for x, x - 2x = -10 - 5 -x = -15 x = 15 years old hope this helps ;)
*October 18, 2013*

**chem 211**

Write the balanced chemical reaction: C2H4 + H2 -> C2H6 , ΔH = -144 kJ/mol C2H4 Then we get the number of moles of C2H4 using the given mass, 14.6 kg of C2H6. Molar mass, C2H6 = 2*12 + 6*1 = 30 g/mol n,C2H6 = 14.6 * 1000 g / 30 g/mol = 486.67 mol Since the mole ratio ...
*October 18, 2013*

**chem**

Recall that the heat absorbed (+) or released (-) by a substance is given by Q = mc(T2 - T1) where m = mass (g) c = specific heat capacity (J/g-K) T2 = final temperature T1 = initial temperature Note that in the problem, the source of energy or heat came from the alloy. Thus ...
*October 17, 2013*

**math**

Let x = capacity of carton Let y = capacity of cup According to the first statement of the problem, x = 2y According to the second statement, 1.8 = 3y + 2x Now, we have the equations. What we'll do is substitute the first equation to the second: 1.8 = 3y + 2(2y) 1.8 = 3y...
*October 17, 2013*

**math**

Yes.
*October 15, 2013*

**math**

y = 3x - 2(4^x) Yep, the derivative of 3x is 3. Yep, it's true that derivative of 2 is 0, but this is not necessary. Note that 2 is multiplied by 4^x, and does not act as a separate term. Yep, the derivative of 4^x is 4^x(ln(4)). Therefore, y' = 3 - 2*(4^x (ln(4))) or ...
*October 15, 2013*

**Science help! URGENT. Check answers**

1. Yes it's false, because velocity is a vector quantity (which depends on magnitude & direction). 2. Yes, it's acceleration and velocity because both are vector quantities.
*October 15, 2013*

**Geometry**

Note that the sum of interior angles of a triangle is equal to 180 degrees. Therefore, we get the sum of angles R, S and T, then equate to 180: (2x + 10) + (2x + 25) + (x - 5) = 180 Solving, 5x + 30 = 180 5x = 180 - 30 5x = 150 x = 30 degrees Hope this helps~ :)
*October 15, 2013*

**math**

For #s 1 and 2: go to wolframalpha . com and type the equation. For #3: To get the slope, we convert the given equation into the form, y = mx + b where m is the slope and b is the y-intercept. Therefore, -2x - 3y = 5 -3y = 5 + 2x y = 5/(-3) + 2x/(-3) y = (-2/3)x - 5/3 Thus the...
*October 15, 2013*

**school of engineering**

i. Acceleration is the change in velocity over time. a = (v,f - v,o) / t where v,f and v,o are the final and initial velocities respectively, and t is the time. Substituting, a = (100 - 50 km/h)*(1000 m / 1 km)*(1 h / 3600 s) / 10 s a = 1.39 m/s^2 ii. Since the motion is ...
*October 15, 2013*

**Math**

Subtract the final temperature to the initial temperature: 8 - (-3) = 8 + 3 = 11
*October 15, 2013*

**geomrtry**

Recall that the sum of exterior angles of any polygon is equal to 360 degrees. Therefore, we just divide 360 by 40 degrees to get the number of sides: 360/40 = 9 sides hope this helps :)
*October 15, 2013*

**Math, Factoring**

(11x + 5)(11x + 5)
*October 12, 2013*

**Calculus - please help!**

Thank you Mr. Steve! :3
*October 11, 2013*

**Inequalities Answer Check**

1. Yep 2. Yep 3. Yep
*October 10, 2013*

**calculus**

Integral (2x^2-4x-6)dx from 0 to 1 = (2/3)x^3 - 2x^2 - 6x from 0 to 1 = (2/3)(1)^3 - 2(1)^2 - 6(1) - ((2/3)(0)^3 - 2(0)^2 - 6(0)) = 2/3 - 2 - 6 - (0 - 0 - 0) = 2/3 - 8 = 2/3 - 24/3 = -22/3 Hope this helps :3
*October 10, 2013*

**6th grade math**

1. You have to just multiply them, because it says 20% of those 50 students got milk, so 50 * 0.2 = 10 students 2. Yep 3. Yep 4. Yep 5. [Unit ratio] What we'll do here is to get the cost per oz. Thus we divide $1 by 3.6 oz and $2.50 by 11.5 oz, then compare. $1/3.6 = $0....
*October 8, 2013*

**math**

Let x = son's age Let 38-x = Mr. Bellini's age (since the sum of their ages must be equal to 38) Set up the equation using the the second statement: (38 - x) - 4 = 5(x - 4) Solving, 34 - x = 5x - 20 34 + 20 = 6x 54 = 6x x = 9 years old (son's age) 38-x = 29 years ...
*October 8, 2013*

**Calculus**

y = log(8x^2-3x+9) Note that derivative of log(x) = 1/(x*ln(10)) Thus, dy/dx = ( 1/(8x^2-3x+9)*ln(10) ) * (16x - 3) = (16x - 3) / ((8x^2 - 3x + 9)*ln(10)) Hope this helps~ :3
*October 8, 2013*

**Calculus**

f(x) = ax^n f'(x) = a*n*x^(n-1) Substitute the given conditions. f'(3) = a*n*(3)^(n-1) 14 = a*n*(3)^(n-1) f'(6) = a*n*(6)^(n-1) 28 = a*n*(6)^(n-1) We can solve this since there are two equations, two unknowns. From the first equation, we can say that a = 14 / n*(3...
*October 8, 2013*

**Calculus**

y = cos^4(pi*t-20) Note that the derivative of cos(x) = -sin(x) and the derivative of x^n = n*x^(n-1). We'll apply them here, and we'll also use chain rule. dy/dt = 4 * pi * cos^3 (pi*t - 20) * (-sin (pi*t - 20)) Hope this helps~ :3
*October 8, 2013*

**Calculus**

y = log(8x^2-3x+9) Note that derivative of log(x) = 1/(x*ln(10)) Thus, dy/dx = ( 1/(8x^2-3x+9)*ln(10) ) * (16x - 3) = (16x - 3) / ((8x^2 - 3x + 9)*ln(10)) Hope this helps~ :3
*October 8, 2013*

**algebra**

Hi. I answered you previous post and it was almost similar, except that here, the roots must be complex/imaginary so D must be less than zero. Anyway, Recall the formula for discriminant. For a quadratic equation in the general form, ax^2 + bx + c = 0, D = b^2 - 4ac if D = 0...
*October 8, 2013*

**algebra**

Recall the formula for discriminant. For a quadratic equation in the general form, ax^2 + bx + c = 0, D = b^2 - 4ac if D = 0 : real, equal/double root D > 0 : two real, unequal roots D < 0 : two imaginary roots Since we're required to have one real root, we equate D ...
*October 8, 2013*

**pre-Algebra**

17x - 22x = 1/2 -5x = 1/2 x = (1/2)/(-5) x = -1/10
*October 8, 2013*

**calcus**

integral (sec u) du This is pretty tricky, but what we'll do here is multiply both numerator and denominator by (sec u + tan u): = integral (sec u * (sec u + tan u)/(sec u + tan u)) du = integral (sec^2 (u) + sec(u)*tan(u))/(sec u + tan u)) du Then we use substitution. Let...
*October 8, 2013*

**calcus**

integral (tan^3 (x) sec^3 (x)) dx Recall the identity, tan^2 (x) = sec^2 (x) - 1 We substitute it here: = integral (tan(x) * (sec^2 (x) - 1)(sec^3 (x))) dx Let u = sec (x) Thus du = sec(x) tan(x) dx Substituting, = integral (u^2 (u^2 - 1)) du = integral (u^4 - u^2) du = (1/5)*...
*October 8, 2013*

**calcus**

integral cos(x) sin(x) dx We simply use substitution. Let u = sin(x) Thus du = cos(x) dx Rewriting, = integral (u du) = (1/2)*u^2 + C = (1/2)*sin^2 (x) + C Or you may also use substitute the formula sin(2x) = 2sin(x)cos(x) to the original, and then directly integrate. Hope ...
*October 8, 2013*

**Calculus**

Hi. I think Mr. Steve had already answered this before (on your previous post), you may want to check it out. I also answered this on that previous post too, but I'll just copy-paste my answer. s = t^6 * tan(t) - sqrt(t) ds/dt = t^6 (sec^2 (t)) + 6t^5 (tan(t)) - (1/2)(1/...
*October 8, 2013*

**Algebra**

7m + mn + 35 + 5n = m(7 + n) + 5(7 + n) = (m + 5)(7 + n)
*October 8, 2013*

**Algebra**

26(5-x)^2 - 5(5-x)^3 = (5-x)^2 (26 - 5(5-x)) = (5-x)^2 (26 - 25 + 5x) = (5-x)^2 (5x+1)
*October 8, 2013*

**Algebra**

by + ay + bx + ax y(b + a) + x (b + a) Note that you can still factor out the (b + a): (b + a)(y + x) Hope this helps~ :3
*October 8, 2013*

**Math**

What do mean? @_@ Anyway, both sides of equation must be equal. I'll just show the step by step. Note that you should always follow the order of which operation comes first: PEMDAS or Parenthesis - Exponents - Multiplication - Division - Addition - Subtraction But there ...
*October 8, 2013*

**Math**

14 = 50 - 42/(3+4) * 6
*October 8, 2013*

**Algebra**

If only two numbers are involved, Let A and B be real, non-zero numbers. 1) (+)A + (+)B = (+) ? This is always true. 2) (-)A + (-)B = (-) ? This is always true. 3) (+)A - (-)B = (+) ? This is always true. 4) (-)A - (+)B = (-) ? This is always true. 5) (-)A - (-)B = (+) ? This ...
*October 8, 2013*

**Calculus**

s = t^6 * tan(t) - sqrt(t) ds/dt = t^6 (sec^2 (t)) + 6t^5 (tan(t)) - (1/2)(1/sqrt(t))
*October 8, 2013*

**Chemistry**

Assuming the gas is ideal, we can use Boyle's law: P1 * V1 = P2 * V2 where P1 = initial pressure P2 = final pressure V1 = initial volume V2 = final volume Substituting, (1.75 atm)(10.7 L) = P2 * 20 L P2 = 1.75 * 10.7 / 20 P2 = 0.936 atm Hope this helps~ :3
*October 8, 2013*

**Chemistry**

Assuming the gas is ideal, we can use Boyle's law: P1 * V1 = P2 * V2 where P1 = initial pressure P2 = final pressure V1 = initial volume V2 = final volume Substituting, (1.75 atm)(10.7 L) = P2 * 20 L P2 = 1.75 * 10.7 / 20 P2 = 0.936 atm Hope this helps~ :3
*October 8, 2013*

**Chemistry 12**

First we get the molar mass of K2CrO4. To get the molar mass, just get a periodic table, find the individual masses of the elements and add them all based on the chemical formula. Thus, K2CrO4: 2*39.1 + 1*52 + 4*16 = 194.2 g/mol Then recall that molarity is equal to moles of ...
*October 8, 2013*

**Algebra 1**

Let x = time in hours Since their costs must be the same, 100 + 15x = 75 + 17x Solving, 100 - 75 = 17x - 15x 25 = 2x x = 25/2 or 12.5 hours Hope this helps~ :3
*October 8, 2013*

**Algebra 1 (Reiny)**

To solve for a, combine all terms with variables on the left side of the equation, and all constants on the right side of equation. Note that when we transpose a term to the other side, its sign becomes the opposite: 12a - 11 = 9a - 1 12a - 9a = 11 - 1 3a = 10 To get a, divide...
*October 7, 2013*

**Chemistry**

First, you must have the specific substance to know its chemical formula (whether it's H2O, NH3, NaOH, etc.) And then you'll get its molar mass. To get its molar mass, just add the individual masses of the elements in the chemical formula. For instance, MM of H2O: 2*1...
*October 7, 2013*

**Math**

I suppose that "XER" means the domain (all possible values of x) is all real numbers. And the answers there are both...wrong. Anyway, range is the set of all possible values of y (or f(x)). Let's analyze each problem. :) a) f(x) = (x^2+3)^2 Note that x^2 can ...
*October 7, 2013*

**Algebra1 Math**

Let x = time in hours Since their costs must be equal, 800 + 16x = 720 + 21x Solving, 800 - 720 = 21x - 16x 80 = 5x x = 16 hours Hope this helps~ :3
*October 7, 2013*

**maths2**

Formula for discriminant: d = b^2 - 4ac note that if d = 0 : real, equal/double root d < 1 : imaginary roots d > 1 : real, unequal roots 7x2 + 3x + 1 = 0 d = 3^2 - 4(7)(1) d = 9 - 28 d = -19 Thus, it's D. imaginary roots. Hope this helps~ :3
*October 7, 2013*

**math**

There are many ways to do this. Graphing is one. Another way is to convert it to the vertex form: y = a(x-h)^2 + k where (h,k) is the vertex and the axis of symmetry is x=h. Thus, y = -4x^2 - 24x - 36 y = -4(x^2 + 6x) - 9 y = -4(x^2 + 6x + 9) - 9 + 9 y = -4(x+3)^2 Thus, V(-3,0...
*October 7, 2013*