Monday

February 20, 2017
Total # Posts: 48,666

**maths equation too hard**

There is no general algebraic way to solve equations like this, but it should be easy to see that 3^3 = 3^3

*February 8, 2017*

**algebra**

c+r = 8.5 16c+8r = 112 Now just solve for c and r.

*February 8, 2017*

**Math**

y is the base Online, use ^ to indicate exponents, as in y^2 and y^4

*February 7, 2017*

**math**

since cos 2?/3 = -1/2, r(2?/3) = 0 So, the graph loops back to r=0 at ?=2?/3 Using symmetry, we need consider only the top half of the figure, so we just need to subtract the inner loop from the outer loop, giving us A/2 = ?[0,2?/3] 1/2 r^2 d? - ?[2?/3,4?/3] 1/2 r^2 d? A = ?[0...

*February 7, 2017*

**math**

It's easier to find the number of quarters: 10*3q + 25q = 385 55q = 385 q = 7 so, d=3q=21

*February 7, 2017*

**Maths**

assuming you meant 1/x + 1/(x+1) = 1 x+1 + x = x(x+1) x^2-x-1 = 0 ...

*February 7, 2017*

**Maths**

y/x * 80p

*February 7, 2017*

**Math**

80/10 = 8 bags

*February 7, 2017*

**math**

possibilities for what? a little more context would help.

*February 7, 2017*

**math**

-7/4 -73/100

*February 7, 2017*

**Geometry**

recall that the diagonals of a rectangle are equal.

*February 7, 2017*

**Math**

You just need to review the meanings of the 1st and 2nd derivatives. y = 3x^4-10x^3+12x^2+12x-7 y' = 12x^3-30x^2+24x+12 = y" = 36x^2-60x+24 = 12(3x-2)(x-1) max/min where y'=0 inflection where y"=0 max if y'=0 and y"<0 min if y'=0 and y"&...

*February 7, 2017*

**math**

3.14*10^8 --------------- = 0.046 or 4.6% 6.8*10^9

*February 7, 2017*

**Math Limits**

(a) 4 (b) 15 (c) -15

*February 7, 2017*

**Math - Continuity of Functions**

(x-2)/(?x-?2) = [(?x-?2)(?x+?2)]/(?x-?2) = ?x+?2 for all x?2 So, if k=2?2 f is continuous everywhere.

*February 7, 2017*

**Maths**

Draw a diagram. It should be clear that h cot60° = (h-10) cot30°

*February 7, 2017*

**Math - Continuity of Functions**

since |sin(1/x)|<=1 x*sin(1/x) -> 0 as x->0 f(0)=0 will make f defined everywhere.

*February 7, 2017*

**math**

Just use the point-slope form and pick any three values for the slope m: y+2 = m(x-6)

*February 7, 2017*

**math**

In retrospect, it would probably have been easier to work this one backwards, with no algebra: After round 3: 10,10,10 After round 2: 5,20,5 and so on...

*February 7, 2017*

**math**

If the start with amounts x,y,z after the 3 rounds, the holdings are x-y-z, 2y, 2z 2(x-(y+z)),4y,2z-(x-(y+z))-2y = 2x-2y-2z, 4y, 3z-x-y 2(2x-2y-2z), 4y-(2x-2y-2z)-(3z-x-y), 2(3z-x-y) = 4x-4y-4z, 7y-x-z, 6z-2x-2y So, now we have three equations: 4x-4y-4z = 10 -x+7y-z = 10 -2x-...

*February 7, 2017*

**maths**

From your sum-to-product formulas, sinA-sinB = 2 cos(A+B)/2 sin(A-B)/2 Using your values, that would be 2 cosx sin2y without knowing more about the relation between x and y, that's as far as we can go. If you supply the missing info, I'm sure you can finish it off.

*February 7, 2017*

**math**

k = m-4 k+3 = 2/3 (m+3) Now just solve for k and m.

*February 7, 2017*

**Math**

"10 to the power of 2" or 10^2 40 + x = 10^2 40+x = 100 . . .

*February 7, 2017*

**Math**

clearly the missing angle is 52° Find two corresponding sides with a known ratio, and use that ratio to find the missing values.

*February 7, 2017*

**science**

static electricity

*February 7, 2017*

**math**

If their ages are a < b < c then c = b+8 a = c-12 a+b+c = 88 ...

*February 7, 2017*

**mensuration**

6^2+8^2 = 10^2

*February 7, 2017*

**Question on Integration**

let x = 2sinh? x^2+4 = 4sinh^2?+4 = 4cosh^2? dx = 2cosh? d? Now the integral becomes ?x^3 / (x^2 + 4)^2 dx ?8sinh^3?/16cosh^4? 2cosh? d? ?tanh^3? d? see what you can do with that. using direct substitution, let u = x^2+4 du = 2x dx ?x^3 / (x^2 + 4)^2 dx (1/2)?x^2 / (x^2 + 4)^2...

*February 7, 2017*

**Algebra**

7d+2b = 11 2d+7b = 16 5d + 2(d+b) = 11 5b + 2(d+b) = 16 add the equations and you get 5(d+b) + 4(d+b) = 27 9(d+b) = 27 d+b = 3 similarly, b-d = 1 b=2 d=1 dog costs $1 burger costs $2

*February 6, 2017*

**Math**

Remember that a proportional relationship between x and y means that y = kx. There can be no extra constants floating around. A is a proportional relationship between y and x^2 Only C is a p.r between y and x. For #2, same thing applies.

*February 6, 2017*

**Algebra2**

Looks good to me

*February 6, 2017*

**Algebra2**

What is the product in simplest form? State any restrictions on the variable. 4a^5/7b^4 times 2b^2/2a^4 My answer is 4a/7b^2 except a=0 and b=0

*February 6, 2017*

**Math**

well, sinØ = 3/4 cosØ = ?5/4

*February 6, 2017*

**Math**

tan(-a) = -tan(a), so tan(a) = 5 so, cot(a) = 1/5

*February 6, 2017*

**Algebra2**

Thank you very much

*February 6, 2017*

**Algebra2**

Simplify the rational expression. State any restrictions on the variable. (n^4-11n^2+30)/(n ^4 -7n^2+10) My answer is n^2-6/n^2-2 except +-sqrt5 and +-sqrt2

*February 6, 2017*

**math**

sorry, an extra point is awarded by scoring an "extra point". A field goal is worth 3 points. At any rate, if they get the extra point after each touchdown, then their score for x touchdowns is y = 6x + 1x = 7x Saying the total score for "x" amount of ...

*February 6, 2017*

**physics**

(6000kg*9.8N/kg)/(4*.10m^2) = 147000N/m^2 = 147KPa

*February 6, 2017*

**physics**

what volume of water has a mass of 400kg? Divide that by 24m^2 to get the depth of the displaced water.

*February 6, 2017*

**physics**

2700 kg * 1m^3/1.25kg = 2160 m^3

*February 6, 2017*

**Accelerated 1**

# coins = c points = p point for star = 3p p = 10c

*February 6, 2017*

**Math**

If you mean y = 9x1/2 it is not even exponential. An exponential function has x in the exponent, such as y = 9 * (1/2)^x which would be decay, because powers of fractions get progressively smaller. If you don't know how to even make a chart, you are in trouble. For a chart...

*February 6, 2017*

**Math**

since time = distance/speed, 7.2*10^2km / 1.2*10^3km/hr = 0.6hr Now convert to minutes.

*February 6, 2017*

**astronomy**

mirrors, lenses

*February 6, 2017*

**Algebra 2 help**

Oh, please. In the first, place, you'd better go out and get a calculator. Or use your phone's calculator. Or, there are lots of calculators online. google, etc. wolframalpha.com allows you to give a formula and a value, such as http://www.wolframalpha.com/input/?i=4x...

*February 6, 2017*

**math help quick please**

stop guessing. Next step: 5x+2x-14 = 7 ... B works for the 1st equation, but not the second.

*February 6, 2017*

**math help quick please**

so, substitute y=x-7 into 5x+2y = 7 5x+2(x-7) = 7 ...

*February 6, 2017*

**Math**

see related questions below.

*February 6, 2017*

**Algebra**

x^3 + 5x^2 - 4x - 2 = (x-1)(x^2+6x+2) The discriminant of the quadratic is positive, so it has two real roots.

*February 6, 2017*

**math**

(3/8) / (3/4) = 3/8 * 4/3 = 1/2 Naturally. Since 1/8 is half as big as 1/4, so are three of them half as big as three fourths.

*February 6, 2017*

**Maths**

I think you meant 4;7;10;13 where An = 1+3n So, just solve for n where 1+3n > 150

*February 6, 2017*

**Algebra**

using the sum of two cubes, (x + 3)^3 + 10 = (x+3+?10)((x+3)^2 - (x+3)?10 + ?100) = x^2 + (6-?10)x + (?100-3?10+9) One root is clearly x = -(3+?10). You can see that the discriminant of the quadratic is negative, so there are no other real roots. Or, consider the graph. It is ...

*February 6, 2017*

**Trig**

since sin(x) = cos(?/2-x) arccos(t) + arcsin)t) = ?/2 In general, draw the triangle. In this case, take cosine of both sides. cos(arccos(t)) = t In your triangle, the adjacent side will be t, and the hypotenuse will be 1. The other leg is thus ?(1-t^2). So, sin(arccos(t)) = ?(...

*February 6, 2017*

**MATH**

The odds are 7:4 beat 4:7 lose, so 4/11 probability

*February 6, 2017*

**Calculus**

This is a trick question, in a way. You can go through the math of height and speed, using an unknown acceleration (you will find that this fails to have a solution when g=9.8 is used). Or, you can just note that since momentum is conserved, the speed at launch is exactly the ...

*February 6, 2017*

**Math**

the unknown sides are equal, say x. So, 54+x+30+x = 134 If you draw your trapezium and mark off the interior 30x30 square, you will find a right triangle at each end, with base 12 and hypotenuse x. So, the height of the trapezium is ?(x^2-144) making the area A = (30+54)/2 ?(x...

*February 6, 2017*

**algebra 2**

you need to get your typing straight × is the symbol for multiplication x is a variable name 9 (9 - 8x) = 2x + 3 81 - 72x = 2x + 3 78 = 74x x = 78/74 = 39/37 Note that you cannot subtract the 2x inside the parentheses. You have to expand the left side first. Try it with ...

*February 6, 2017*

**algebra 2**

[-4b -8] + [-1b -b^2] + 2b^3 plug in b=2 (-4(-2) - 8) + (-1(-2) - (-2)^2) + 2*(-2)^3 (8-8) + (2-4) + 2(-8) 0 - 2 - 16 -18

*February 6, 2017*

**Math**

400 mL of 1/2 strength juice contains 200 mL of juice Adding 100 mL of juice makes 500 mL containing 300 mL juice, or 60% juice.

*February 6, 2017*

**math**

Change the fractions to have the same denominator: 1/3 , 5/6 , 4/3 = 2/6, 5/6, 8/6 The numerators are 2,5,8 Clearly, 3/6 = 1/2 is added each time.

*February 6, 2017*

**Maths**

density of A: 1.2kg/(20*10*5)cm^3 = 1.2/1000 = 0.0012 kg/cm^3 = 1.2 g/cm^3 Block B is 6cm on a side, with a density of 1.2*1.4 = 1.68 g/cm^3 So, its mass is 1.68 g/cm^3 * 216cm^3 = 362.88 g = 0.36 kg

*February 6, 2017*

**math**

The amount of work is 8hr/day * 13men * 15day = 1560 man-hr So, you want x so that 10*26*x = 1560 x = 6 days

*February 6, 2017*

**Algebra (plz)**

(a+b)^2 = a^2 + 2ab + b^2 You need the first and last terms to be perfect squares, and the middle term to be twice their product. 4m^2-4mp+p^2 = (2m-p)^2 16s^2+56s+49 = (4s+7)^2 16c^2+72cd+81d^2 = (4c+9d)^2

*February 6, 2017*

**las st**

The vertical and horizontal distance components of the flare are y = 2400 + 120t - 4.9t^2 x = 207.84t The flare hits the ground when t=37.54 The tangent of the angle of direction at time t=37.54 is dy/dx = (120-9.8*37.54)/207.84 = -1.193 So, ? = -50° I am assuming that the...

*February 6, 2017*

**Math**

Hmmm. If m is the number of correct answers, then s = 5m-3(10-m) = 8m-30

*February 5, 2017*

**math**

I expect some information about g will help ...

*February 5, 2017*

**Intermediate Algebra**

same problem: If there are x liters of 25%, then the rest (50-x) is 60%. So, .25x + .60(50-x) = .40 * 50

*February 5, 2017*

**Algebra**

48/5

*February 5, 2017*

**Math**

it gains 1 meter each day. After 9 days it has climbed 9 meters On the 10th day it climbs 3 meters and is out.

*February 5, 2017*

**Math**

so, is -18 the max or the min? There is a double root at x=1, where it just touches the x-axis. It crosses the x-axis at x = -4 Since this is a cubic polynomial, with negative leading coefficient, it drops down from the left. So, it is decreasing on (-?,-4) and beyond to the ...

*February 5, 2017*

**Algebra**

the math looks good so far. Note that 99+77 is only half the perimeter.

*February 5, 2017*

**Geometry**

looks good so far.

*February 5, 2017*

**Math**

Check here: http://www.wolframalpha.com/input/?i=1%2F2+(+x%5E2-2x%2B15) Use what you know about quadratics to figure out what it shows. You can play around with other functions and see how things work...

*February 5, 2017*

**pre calc**

Too bad you didn't see fit to show your work... f(x) = 1/3 ?(1-2x) g(x) = (x-2)/x (g?g)(x) = g(g(x)) = (g-2)/g = ((x-2)/x - 2)/((x-2)/x) = 1 - 2x/(x-2) (g?f)(x) = (f-2)/f = (1/3 ?(1-2x) - 2)/(1/3 ?(1-2x)) = 1 - 6/?(1-2x) (g?g)(3) = 1 - 6/1 = -5 (g?f)(-24) = 1 - 6/7 = 1/7 (...

*February 5, 2017*

**Algebra**

Write an equation in point-slope form to represent each situation. Assume a linear relationship between the given quantities. A temperature of 50 degrees Fahrenheit corresponds to 10 degrees Celcius. A temperature of 77degrees Fahrenheit corresponds to 25 degrees Celsius. ...

*February 5, 2017*

**Algebra**

Thank you so much I found my mistake l added 10 to 2010

*February 5, 2017*

**Algebra **

Write an equation in slope-intercept form fo each situation. Assume a linear relationship between x and y. In 2007 Tamara bank account balance was $500. In 2010, it was $1,400. Assuming she saves the same amount each year, in what year will her balance be 3,500?

*February 5, 2017*

**9th grade alebra**

whole and natural exclude negative values, so C is the choice

*February 5, 2017*

**Algebra**

Thank you

*February 5, 2017*

**Algebra**

For each linear relationship identify the independent and dependent variables. Then calculate the rate of change / slope for each situation. Christopher has saved $65 after 3 weeks and $98 after 6 weeks.

*February 5, 2017*

**Maths**

you can construct a 60° angle, I'm sure. (make an equilateral triangle) Bisect that twice and you have a 15° angle Construct a right angle and subtract the 15° angle from that. Now you have your 75° angle, so just draw that angle with the sides as given ...

*February 5, 2017*

**addmaths**

well, no real roots means that the discriminant is negative. So you need (4m)^2-4(1)(2m+1) < 0 16m^2-8m-4 < 0 4m^2-2m-1 < 0 The roots of that quadratic are (1±?5)/4 So, the discriminant is negative when (1-?5)/4 < m < (1+?5)/4

*February 5, 2017*

**Math**

the sector will be a 1/4 circle of radius 24...

*February 5, 2017*

**Algebra2**

thank you

*February 4, 2017*

**Algebra2**

The amount of oil used by a ship traveling at a uniform speed varies jointly with the distance and the square of the speed. The ship uses 30 barrels of oil in traveling 85 miles at 42 mi/h. How many barrels of oil are used when the ship travels 26 miles at 54 mi/h? Round your ...

*February 4, 2017*

**Math**

36x^4 - 3x^3 - 18x^2 3x^2 (12x^2-x-6) 3x^2 (4x-3)(3x+2) 9x^2 + 3xy - 2y^2 (9x+)(x-) won't work; the 9 is too big 3*2 - 3*1 = 3, so (3x+2)(3x-1)

*February 4, 2017*

**natural science**

mass = density * volume, so since the two masses must be equal, the volume v we want is found by 8.96v = 11.4*1.15

*February 4, 2017*

**Algebra**

well, just plug and chug. .5 = 1/2 .5^2 = 1/2^2 = 1/4 .5^3 = 1/2^3 = 1/8 p^2q^2+pq–q^3–p^3 (1/4)(1/4)+(1/2)(-1/2) - (-1/8) - 1/8 1/16 - 1/4 + 1/8 - 1/8 -3/16

*February 4, 2017*

**algebra**

In thousands, let t be the number of years since 2009, since that is the year we have our first appraisal. V(t) = 475+(468-475)/(2014-2009) t = 475 - 1.4t But we want t to be years since 2005. That means we have to add back 4 more years of loss: 4*1/4=5.6 V(t) = 480.6 - 1.4t ...

*February 4, 2017*

**Algebra**

85(z-66) = z+10 why do you use all those words, when the math is so much clearer?

*February 4, 2017*

**Algebra**

The numbers are x and x+2 x + x+2 = -126 ...

*February 4, 2017*

**algebra**

as written, it is not an exponential function. Try using ^ for exponents and * for multiplication, as in 4 * 2^x

*February 4, 2017*

**math**

1.1 * 0.8 = 0.88 now you can get the change.

*February 4, 2017*

**Math**

|x+1| = |x-(-1)| That is the distance from x to -1 So, on the number line, mark the two points which lie 3 units away from -1: -4 and +2 Shade the area between those two points, where the distance from -1 is less than 3.

*February 4, 2017*

**Math**

Of course there is, though its form will depend on how the trapezoid is described. For simplicity, let's say that the bottom base goes from (0,0) to (a,0) and that the top base goes from (b,h) to (c,h). (Usually, this will mean that 0<=b<=c<=a) The area of the ...

*February 4, 2017*

**Calculus**

Just use the normal product and chain rules, with the chain rule: f=uv, f' = u'v+uv' f=u/v, f' = (u'v-uv')/v^2 Just take it a step at a time; you know how to get the derivatives of the various function involved. If you get stuck, come back with your ...

*February 3, 2017*

**Calculus**

just use the chain rule (a) h' = f'g + fg' = (12)(-3)+(-7)(-9) = 27 (b) h' = (f'g-fg')/g^2 = ((12)(-3)-(-7)(-9))/(-3)^2 = -11 (c) h' = (g'(1+f^2))-g(2ff'))/(1+f^2)^2 = ((-9)(1+(-7)^2))-(-3)(2(-7)(12))/(1+(-7)^2)^2 = -281376/625

*February 3, 2017*

**Algebra2**

thank you

*February 3, 2017*

**Algebra2**

Solve the equation 3^5sqrt(x+2)^3+3=27 My answer is 30

*February 3, 2017*