Monday

June 27, 2016
Total # Posts: 41,458

**Algebra**

differences: 1 3 5 7 2 2 2 so, the function is a quadratic
*April 15, 2016*

**math.**

x is 3 if x < 3 x is 4 is x >= 3 Given so few points, it is possible to posit any number of rules.
*April 15, 2016*

**Math**

2(w + 5w-8) = 140 find w, then the length. Volume is l*w*d
*April 15, 2016*

**math**

Just list them: 3+3+3+3+3 3+3+3+3+2+1 ... 1+1+1+1+1+1+1+1+1+1+1+1+1+1+1
*April 15, 2016*

**algebra**

you have the intercepts. Plot those two points and draw a line through them. That is the graph.
*April 15, 2016*

**pc parabola**

I'd have stopped a step earlier: y = (x+4)^2/38 - 121/38
*April 15, 2016*

**Math**

I'd say yes, except for that pesky minus sign. I suspect a typo. D is correct if the original expressions is -x(5x-4)
*April 15, 2016*

**Math**

some kind of logistic function
*April 15, 2016*

**maths**

m = s+4 m+8 + s+8 = 3(m+s) or, m-s = 4 m+s = 8 m = 6
*April 15, 2016*

**mats**

5(a+4d) = 6(a+5d) a = -10d T11 = a+10d = 0 check: a=10, d=-1 10,9,8,7,6,5 5*6 = 6*5 a=-5, d=1/2 -5,-4.5,-4,-3.5,-3,-2.5 5(-3) = 6(-2.5) = -15 In both cases, T11 = 0
*April 15, 2016*

**Percent**

If the true value was 50, then Julian got 52.5 Amanda got 47.5 Clearly the actual and percent errors were the same in both cases. Julian's error was +5%, Amanda's was -5%
*April 15, 2016*

**maths**

e^x = x since e^x is always positive, there are no negative roots. Since the slope of y=x is 1, and the slope of y=e^x is greater than 1 for positive x, then since e^0>0, the two graphs never intersect. In short, there are no real solutions.
*April 15, 2016*

**Science**

would that be Capt. Jack Sparrow?
*April 15, 2016*

**math**

You have a scaled-up 3-4-5 right triangle.
*April 15, 2016*

**Percent error math**

surely the change would be 5 * -3/2 = -15/2
*April 15, 2016*

**maths**

The question as stated has no solution. clearly the boys' %age is 80% of the girls'
*April 15, 2016*

**Math**

well, sin(2t) varies from -1 to 1.
*April 15, 2016*

**Math Trig**

correct. How can you be stuck there? Surely by the time you have learned trigonometry, you know how to work with fractions ... ? hint: 1 = 169/169
*April 14, 2016*

**Algebra**

j = 3g g = b/2 s = 2(j+b) s = 60 solving those, we get Greg is 6. So, Jane is 8.
*April 14, 2016*

**Math**

she rose 3*25 = 75 ft clearly she started up from -195-75 = -270 ft
*April 14, 2016*

**Math**

24:18 = 4:3
*April 14, 2016*

**physics**

surely you remember the first formula ever taught in physics: F = ma just plug in your numbers.
*April 14, 2016*

**Math**

Looks like 0.4 * 0.75
*April 14, 2016*

**Precalculs**

4x^2/36 + 49y^2/36 = 1 x^2/9 + y^2/(36/49) = 1 a = 3 b = 6/7 c^2 = a^2-b^2 = 9-36/49 = 405/49 c = 9√5/7 You found the vertices ok. They are at (±a,0) The foci are at (±c,0)
*April 14, 2016*

**math**

google is your friend. You can start here: http://mathforum.org/library/drmath/view/51708.html
*April 14, 2016*

**Algebra**

8n^2 - 6n + 7n^2 - 4n +5 8n^2+7n^2 -6n-4n + 5 15n^2 - 10n + 5 do the 2nd one the same way. Collect all the terms with the same powers, then add up the coefficients.
*April 14, 2016*

**Polynomials**

(m^2 – m + 3) + (m – 1) m^2-m+3+m-1 m^2-m+m+3-1 m^2+2 (4x^2 – 2x – 1) – (–3x^3 + 2) 4x^2-2x-1+3x^3-2 3x^3+4x^2-2x-1-2 3x^3+4x^2-2x-3
*April 14, 2016*

**Help please**

they are the numbers multiplying the variables. so, -4 is just a constant, not a coefficient. 5,2 are the coefficients.
*April 14, 2016*

**Math - Please check!**

they all look good to me.
*April 14, 2016*

**Maths-equation**

Try letting a = x+y b = y+z c = x+z Then you have a+b = 5ab b+c = 7bc a+c = 6ac Now see what you can do with that.
*April 14, 2016*

**Math**

The 1st alloy (x) is 2/5 iron and the 2nd alloy (30-x) is 7/10 iron. So, you want to mix 'em up so that (2/5)x + (7/10)(30-x) = (1/2)(30) x = 20 Check: 20 oz of Alloy 1 contains 8 oz iron 10 oz of Alloy 2 contains 7 oz iron. Total is 15 oz in 30 oz of the mix, or a ratio ...
*April 14, 2016*

**Maths- Calculus**

if you want the volume, that would be, using shells, ∫[0,∞] 2πrh dx where r=x and h=y=e^-x ∫[0,∞] 2πxe^-x dx = -2π(x+1)e^-x [0,∞] = 2π using discs, it is ∫[0,1] πr^2 dy where r = x = -ln(y) ∫[0,1] π(lny)^2...
*April 14, 2016*

**Calculus**

the volume would be ∫[-√5,√5] πr^2 dx where r=y=(5-x^2) Because of symmetry, that is 2∫[0,√5] π(5-x^2)^2 dx = 80π√5/3 using shells, that is 2∫[0,5] 2πrh dy where r=y and h=x=√(5-y) 2∫[0,5] 2πy√...
*April 14, 2016*

**Algebra**

this link is a nice long division calculator: http://calc101.com/webMathematica/long-divide.jsp
*April 14, 2016*

**maths**

Let the total distance be 2d. Then, since time = distance/speed, d/100 + d/90 = 1/3
*April 14, 2016*

**Geometry**

what is the "radius" of a square? Circles have a radius. Squares have a side and a diagonal.
*April 14, 2016*

**Math**

as with all polynomials, it is D
*April 14, 2016*

**Solid Mensuration 04/15/16**

since DE and BC are parallel, triangles ABC and ADE are similar. The ratio of sides of ADE to ABC = 28/70 = 2/5 So, CE = AC * 3/5 = 15 BD = AB * 3/5 = 9
*April 14, 2016*

**math**

what, never done a proof? (C)!
*April 14, 2016*

**maths simultaneous equation**

My previous solution of x=y=z=0 works, but was derived in error. The other solution is x = 5/24 y = 7/24 z = 1/24 x+2y+z = 5xy + 5xz + 5y^2 + 5yz x+y+2z = 7xy + 7xz + 7yz + 7z^2 2x+y+z = 6x^2 + 6xy + 6xz + 6yz Now just start substituting.
*April 14, 2016*

**mathematics-combination vs A.P**

n(n-1)(n-2)(n-3)(n-4)/5! - n(n-1)(n-2)(n-3)/4! = n(n-1)(n-2)(n-3)(n-4)(n-5)/6! - n(n-1)(n-2)(n-3)(n-4)/5! place all over a common denominator of 6! and then you have a polynomial of the 6th degree. Try a few easy values with synthetic division (0,1,2,3) and you can reduce the ...
*April 14, 2016*

**Math**

If he started with $x, then (1/5)(3/8 x) = 60 x = 800 After the spending he had left 800(1 - 5/8 - (1/5)(3/8)) = 240 why do you ask what it means? You presumably are calculating how much was left at the end.
*April 14, 2016*

**math**

http://www.learningace.com/doc/6138186/5b99373c5323a0518f25b611d97ade45/wallis-s-formula-to-integrate-powers-of-sine-or-sine-0-pi-2 is a good place to start. Try adjusting the interval to fit your needs.
*April 14, 2016*

**Calculus 1**

y' = b(1-ax)e^(-ax) 1-ax=0, at x=1/a = 4, making a = 1/4 y(4) = 4be^(-4/4) = 12 4b/e = 12 b = 3e y = 3ex e^(-x/4) verify this at https://www.wolframalpha.com/input/?i=y%3D3ex+e^%28-x%2F4%29
*April 13, 2016*

**Calculus I**

lim (√(ax+b)-9)/x = lim a/(2√(ax+b)) so, since we afre clearly dealing with lim = 0/0, we need √(ax+b) = 9 ax+b = 81 a/(2√(ax+b)) = 1 a = 2√(ax+b) a^2 = 4(ax+b) a^2 = 4*81 a = 18 so, b=81 lim (√(18x+81)-9)/x = 1 verify at https://www....
*April 13, 2016*

**Math**

so, plot a few points and draw the curve.
*April 13, 2016*

**maths simultaneous equation**

clearly x = -y = -z y = -z so, they are all zero.
*April 13, 2016*

**math**

horizontal: hexagon vertical: rectangle (pencil is unsharpened!)
*April 13, 2016*

**Math**

the slopes are Dixie: 20/60 = 1/3 Bell: 40/60 = 2/3 Liberty: 30/60 = 1/2 Bell is the steepest. Choice (A)
*April 13, 2016*

**English**

correction History*
*April 13, 2016*

**English**

1. Englishmen expected to have a ___ in their government. 2. The __ was the first legislature in the Jamestown colony. 3. The Massachusetts colonist legislature was the ____. 4. In Pennsylvania, England gave _____ to William Penn. 5. Even though the governor and large council ...
*April 13, 2016*

**Geometry Honors**

no deviation to that formula. Maybe you'd like the derivation... Draw a radius r, extended by h. Draw a second radius r. Connect the two endpoints, and that is the distance to the horizon. d = √((r+h)^2-r^2) = √(2rh+h^2) That's the distance in km. Usually h...
*April 13, 2016*

**Math**

a/(b+g) = 5/6 b/g = 2/5 g = b+36 b/(b+36) = 2/5 b=24 so, g=60 a/84 = 5/6 a = 70
*April 13, 2016*

**Math**

try using the letter x for the variable, not the multiply operator. Since all the choices are linear, check for the slope of the line. as x increases by 1, y increases by 3. So, look for y = 3x Now, if x=0, 3x=0, but y is 3. So, we need to adjust things, leaving the 3x alone: ...
*April 13, 2016*

**math**

Not enough to go on. Depending on the initial speed, the rocket could be almost anywhere, on its way up or down, at a variety of heights. If the initial speed was v, then you have the parabola and line y = -1.112/v^2 x^2 + 0.335x y = 0.662(x-1670) The value of v can change ...
*April 13, 2016*

**Algebra. NEED HELP ASAP PLEASE**

-65 <= F <= 60 -65 <= 9/5 C + 32 <= 60 -97 <= 9/5 C <= 28 -53.89 <= C <= 15.56
*April 13, 2016*

**Math **

for the quadratic, note that f(-1) = f(1) = 4 That means the vertex lies on the line x=0. y = a(x-0)^2 + c or, y = ax^2+5 Now use one other point to get a: 1 = 4a+5 a = -1 y = -x^2+5
*April 13, 2016*

**Calculus**

f(x) increases where f'(x) > 0. f(x) is concave up when f"(x) > 0.
*April 13, 2016*

**Math**

brute force way: n + n+2 + n+4 + n+6 = 296 using progressions: 4/2 (2n+3*2) = 296 In either case solve for n, and the next number is n+2
*April 13, 2016*

**Maths**

looks good to me, if all the cricket players also play football.
*April 13, 2016*

**Maths**

A set of n elements has 2^n subsets, including the empty set. So, if you have 4 fillings, and want at least one, that will allow for 2^4-1 = 15 different combinations, using 1 to 4 items. add in the totally plain one, and that gives 16 ways to make the sandwich. (not sand which!)
*April 13, 2016*

**math**

remember that the terms have a constant ratio, so (2k-28)/(k-6) = (k-6)/k Now just solve for k. You will get two answers, only one of which makes all the terms positive.
*April 13, 2016*

**Integers**

or, using what you know about arithmetic progressions, 6/2 (2a+5*1) = 171 a = 26 so the numbers are as shown above.
*April 12, 2016*

**Math**

Medi* comes off before taxes, so 22.48 + 52.72 + 0.23(1625.35-22.48-52.72) = 431.73
*April 12, 2016*

**Math**

just divide the deposit by the total: 175/625 = 0.28 = 28%
*April 12, 2016*

**Math**

well, g(1) = int{1,1} f(t)dt if the integral is done over an interval of zero width, its value is zero.
*April 12, 2016*

**Math**

just subtract the field from the total: (8x)(12x) - (3x)(6x) = 96x^2 - 18x^2 = 78x^2
*April 12, 2016*

**Please HELP! Calculus (Implicit functions)**

or, using implicit, 16x^2 - 8xy - x + y^2 = 0 32x - 8y - 8xy' + 2yy' = 0 (2y-8x)y' = 8y-32x dy/dx = (4-16x)/(y-8x) dx/dy = (√x+4x-8x)/(4-16x) = (1/4)(√x-4x)/(1-4x) Check my math and see whether these agree.
*April 12, 2016*

**Please HELP! Calculus (Implicit functions)**

switch variables and solve for y, and you get (after squaring) 16y^2 - (8x+1)y + x^2 = 0 y = [(8x+1)±√(16x+1)]/32 Pick the branch you want and take the derivative. Using the + branch, y' = 1/4 (1 + 1/√(16x+1))
*April 12, 2016*

**Math**

some kind of exponential would do it. So, with t as time since 1998, f(0) = 72000 f(2) = 70379 f(∞) = 60000 f(t) = 60000 + 12000 e^-kt now we need k so that f(2) = 70379 60000 + 12000 e^-2k = 10379 k = 0.073 So, f(t) = 60000 + 12000 e^(-.073t)
*April 12, 2016*

**try,check,and revise**

If Carly had c, the Rob had c-4. So, c + c-4 = 42 2c = 46 c = 23 So, Carly had 23 and Rob had 19
*April 12, 2016*

**Calculus Help Stuck Part 2?**

or, consider x-64 as the sum of cubes: x-64 = (∛x)^3 - 4^3 so it factors into (∛x-4)(∛x^2+4∛x+16) Now the fraction is just 1/(∛x^2+4∛x+16) = 1/(16+16+16) = 1/48
*April 12, 2016*

**Calculus Help Stuck Part 2?**

(∛x-4)/(x-64) -> 0/0 so try L'Hospital's rule. Then the limit is (1/(3∛x^2) / (1) = 1/(3*16) = 1/48
*April 12, 2016*

**try,check,and revise**

27+3x
*April 12, 2016*

**math**

(1-2i)(1+2i) = 1^2+2^2 = 5 (1-i)(1+i) = 1^2+1^2 = 2 5*2 = 10
*April 12, 2016*

**algebra/math**

surely you have learned how to solve a quadratic equation, or you'd not have been given this exercise. x^2+6x + 9 = 24 x^2+6x-15 = 0 x = (-6±√96)/2 = -3±2√6 clearly, -3-2√6 is less than -3+2√6
*April 12, 2016*

**algebra**

since (a-bi)(a+bi) = a^2+b^2, we have (15-20i)(1+2i) ------------------ (1-2i)(1+2i) = (15-20i+30i-40i^2)/(1^2+2^2) = (55+10i)/5 = 11+2i
*April 12, 2016*

**Math**

well, solve the equation and pick the smaller value. I hope you are not expecting integers.
*April 12, 2016*

**math**

well, (x + 7/2)^2 = x^2 + 7x + 49/4
*April 12, 2016*

**Trigonometry**

draw a diagram. Then it will be clear that your distance x can be found by 1200/x = sin32°
*April 12, 2016*

**Graphs**

The points on f(2x) are half as far from the y-axis as those of f(x)
*April 12, 2016*

**Math**

depends on the shape of the volume, eh?
*April 12, 2016*

**math**

see whether you get what wolframalpha does: https://www.wolframalpha.com/input/?i=solve+%28x-2%29^2+%2B+%28y-7%29^2+%3D+169,+x-2y%3D10
*April 12, 2016*

**math**

all points (x,y) that are 13 units away from the point (2,7) defines a circle: (x-2)^2 + (y-7)^2 = 169 so, the line x-2y=10 may intersect the circle in 0,1, or 2 points. So, plug x=2y+10 into the equation of the circle and see where the two graphs intersect.
*April 12, 2016*

**math**

well, they intersect where f(x) = g(x). x^3-x^2+x+1 = x^3+x^2+x+1 -x^2 = x^2 x = 0 to check, see https://www.wolframalpha.com/input/?i=x^3-x^2%2Bx%2B1+%3D+x^3%2Bx^2%2Bx%2B1
*April 12, 2016*

**Math 142 (Pre-Cal) (Circles)**

the circumference is 2pi*10 = 62.83cm So, multiply that by the number of times the wheel turns in 15 seconds.
*April 12, 2016*

**Math/geometry**

since the angles x and y are complementary, x+y = 90 y = 3x+6 now just solve for x and y.
*April 12, 2016*

**Geometry**

since the circle has area πr^2, and the sphere has surface area 4πr^2, what do you think?
*April 12, 2016*

**Algebra**

A linear equation is y=mx+b where x is the sales, b is the base pay, and m is the percentage used to find the commission. We have 560 = m*800 + b 460 = m*460 + b 540 = m*540 + b 600 = m*1000 + b Those points do not fit any linear equation. Check for typos.
*April 12, 2016*

**Maths Ms sue**

300+10+16+22+... = 310 + 19/2 (2*16 + 18*6) = 1640
*April 12, 2016*

**math**

can you not check your answers? (-4,8) works (5,35) works
*April 12, 2016*

**Geometry - incomplete**

No idea where CDE are in relation to BGF. All you have said is that the two squares share corner A. However, you do know that the smaller square has sides 1/2 as long as the larger one, so its area is 1/4 as big. I suspect you can use that to determine the shaded area. Also, a...
*April 12, 2016*

**Algebra 1**

Who needs a teacher? Just think a bit. Where is the ball to start with? At the top of the cliff. That's when t=0. So, plug in 0 for t and evaluate.
*April 12, 2016*

**math**

they all express a ratio, but I'd guess C is least likely to be used.
*April 12, 2016*

**Math**

can't quite parse your text. It's probably one of 976 + 2n or 9762n
*April 12, 2016*

**Math**

if the angle is x, then it is opposite the shortest side. tan(x) = 5/8
*April 12, 2016*

**Math**

P(blue) = 3/12 * 2/11 P(>= 1 blue) = 1-P(no blue) = 1 - (9/12 * 8/11)
*April 12, 2016*

**algebra. someone please explain to me please!**

since time = distance/speed, d/12 + d/6 = 6
*April 12, 2016*

**Pre calculus**

what about the uphill anchor point? I assume the antenna is vertical. Anyway, if the uphill anchor point is x feet from the base, then we have uphill cable length is u, where u^2 = x^2+100^2 - 2*100x cos 78° downhill cable length d is d^2 = 95^2 + 100^2 - 2*95*100 cos102°
*April 12, 2016*

**algebra**

900 + .07(x-1000) = 2900
*April 12, 2016*