# Posts by STEVE

Total # Posts: 49,527

**Math**

just as with the rectangle, area = base * height

*February 23, 2017*

**MATHS**

looks more like 1/(6n-3)

*February 23, 2017*

**MATHS**

look at the denominators: 3,9,15,21,27, ...

*February 23, 2017*

**Physics - eh?**

Maybe one of the more expert physicists can decipher your convoluted sentence. I cannot.

*February 23, 2017*

**math**

because they have mass of 45.45 kg, and gravity pulls them with the force of 100 lbs.

*February 23, 2017*

**Maths**

oops. well, use the GP formulas instead. Same idea.

*February 23, 2017*

**Maths**

4/2 (2a+3d) = 312 a + a+3d = 252 now solve for whatever numbers you are interested in.

*February 23, 2017*

**Algebra**

the domain of all polynomials is (-?,+?) for rational functions, it is the same, except where the denominator is zero. f*g = (x^2+3x-4)(x+4) f/g = (x^2+3x-4)/(x+4)

*February 23, 2017*

**Calculus**

you have integral x^(1/3) dx by the power rule, that is (3/4) x^(4/3) + C Choice A is correct. In fact that is your answer, but you did not recognize it! It's always sad to get a question wrong, but to miss it when you got it right is tragic.

*February 23, 2017*

**Math - Derivatives**

huh? Let's take f=1/u. (Let u=x+1 or u=x-1) f = 1/u = u^-1 f' = -1 u-2 f" = (-1)(-2)u-3 ... fn = (-1)nn! u-(n+1)

*February 23, 2017*

**Math - Derivatives**

so, did you even think about the hint? 2x/(1-x^2) = 2x/((1-x)(1+x) = -[1/(x+1) + 1/(x-1)] The nth derivative of 1/(x+1) and 1/(x-1) is easy to figure, right?

*February 23, 2017*

**math**

well, f(0) = d so, d = -18 no idea on the values of a,b,c ... You need more information.

*February 23, 2017*

**math**

f = x^3+x^2+bx+18 f' = 3x^2 + 2x + b f'(1) = 3+2+b = 5+b Since y = -8x+20 is tangent at x=1, it has the same slope as the curve there. So, 5+b = -8 b = -13 I have no idea where a comes into play, but maybe you can work it in and include it in the solution.

*February 23, 2017*

**math**

10% discount means he paid 90%. Total cost of the goods is 1.25 * 42000 + 10*22000 = 272500 He paid 90% of that, which is 0.90 * 272500 = ?

*February 23, 2017*

**value**

many people attend.

*February 22, 2017*

**precalculus, complex numbers**

This problem is discussed here: http://math.stackexchange.com/questions/2144834/let-alpha-omega-omega2-omega4-and-beta-omega3-omega5 google is your friend. Try using it.

*February 22, 2017*

**Math**

4 small cubes will fit into a 1-ft length. So, 4^3 = 64 small cubes will fit into each cubic foot. 64*77 small cubes fit into 77 ft^3. Assuming the dimensions of the large solid are multiples of 3 inches ...

*February 22, 2017*

**Math**

at least 40" tall means that h >= 40 So, those who cannot ride are less than 40, or h < 40 Not <= 40, since the 40" kids can ride.

*February 22, 2017*

**maths**

you can construct a right angle by constructing a perpendicular bisector. Or, google will show you many other ways. Then just measure your distances.

*February 22, 2017*

**Math. Fair race project help!**

Looks to me like man: 45t the anime elk is just a cartoon, so its speed doesn't matter ... why the emphasis on a fair race? Is someone cheating?

*February 22, 2017*

**Maths**

7/2 (2a+6d) = 13/2 (2a+12d) 7a+21d = 13a+78d 6a + 57d = 0 2a + 19d = 0 S20 = 20/2 (2a+19d) = 0

*February 22, 2017*

**Maths**

If you mean log(9^3/4^3), it is certainly not log2 If not, try fixing it up with real math notation, so we can see what you do mean...

*February 22, 2017*

**math**

see related questions below.

*February 22, 2017*

**Differential equations,Calculus**

yes, c=k, so if k = 5?/4, t = k (1 - 1/r) = 5?/4 (1 - 1/r)

*February 22, 2017*

**maths**

huh. the numbers are 5x and 7x, but 7 does not divide 120. ???

*February 22, 2017*

**computer programming**

for i=1 to 10 read n[i] for i=10 to 1 step -1 print n[i] Or, if you don't like counting down, for i=1 to 10 print n[11-i] or, depending on the language, the array may be 0-based, but you can allow for that.

*February 22, 2017*

**Math**

density is people/mi^2, so just divide the population by the area...

*February 22, 2017*

**Algebra**

so, it is 10^6 as big, or a million times.

*February 22, 2017*

**Physics**

conserve momentum: 0.5*10 + 0.5*0 = (0.5+0.5)*v And Lose All Of Those Ridiculous Capital Letters!

*February 22, 2017*

**math**

Note that each fraction is of the form n/(2n+1) This can be written as 1/2 - 1/(2(2n+1)) clearly, as n gets larger, a smaller amount is subtracted, so the fraction with the largest denominator is the largest -- closer to 1/2

*February 21, 2017*

**parabolas**

42

*February 21, 2017*

**Calculus**

let x = 4tan? ?(16+x^2) = 4sec? dx = 4sec^2? d? it gets much simpler.

*February 21, 2017*

**Calculus**

let x = 5 sec? dx = 5 sec? tan? ?(x^2-25) = 5 tan? x^2 = 25 sec^2? Things will get much simpler.

*February 21, 2017*

**Algebra**

the angles are x, 4x+2, 3x-6 they add up to 180, so ...

*February 21, 2017*

**Math**

note the pattern. 9 is 8+1, so: 9*1 = 8*1 + 1 9*2 = 8*2 + 2 ... 9*7 = 8*7 + 7

*February 21, 2017*

**Algebra**

If it takes Joe x minutes alone, then 1/35 + 1/x = 1/15

*February 21, 2017*

**Statistics**

they are doomed -- Doomed!

*February 21, 2017*

**math**

well, 15-5 = 10 is 10 < 5 ?

*February 21, 2017*

**math**

both correct.

*February 21, 2017*

**Math derivatives**

(f?g) = f(g) so, (f?g)' = df/dg * dg/dx (f?g)(2) = f'(g(2)) * g'(2) = f'(4) * g'(2) = 8*6 = 48 if you're still unsure, use an example f(x) = sin(x) g(x) = x^2 (f?g)(x) = sin(x^2) (f?g)' = cos(x^2) * 2x and the logic above makes sense

*February 21, 2017*

**Algebra**

3.96/16 = .2475 direct variation has a relation written as y = kx tax = .2475 * price

*February 21, 2017*

**Come on**

I think you need to provide a bit more context in your posts. They make no sense as written

*February 21, 2017*

**math**

what is s? the number of sales? If so, income is selling price * # tickets: inc = x(1800-140x) profit = income - expenses, so ...

*February 21, 2017*

**Science**

it stays constant

*February 21, 2017*

**Algebra/Math**

b/2

*February 21, 2017*

**Math**

did you actually read the Remainder Theorem? It says that the remainder when P(x) is divided by (x-a) is P(a). So, you want to just plug in -3 for x. P(-3) = (-3)^4-9(-3)^3-5(-3)^2-3(-3)+4 = 81+243-45+9+4 ...

*February 21, 2017*

**Math**

(36/8) * 2 = ?

*February 21, 2017*

**Maths**

2^2 * 2^3 = 2^5 = 32

*February 21, 2017*

**Math**

This appears to be a problem involving direct variation. So, you know that the equation will look like v = kt k represents the rate of fill, in liters/min. Since v(2) = 200, 200 = 2k, so k=100 Thus, the final equation must be v = 100t

*February 21, 2017*

**math**

d = 20 r+g = 2d g+d = 3r so, r+g = 40 3r-g = 20 4r = 60 r = 15 g = 25

*February 21, 2017*

**Physics**

s = 1/2 at^2 so, 1/2 * a * 2^2 = 10 a = 5 m/s^2 assuming, of course, that the block slid the entire length of the plane ...

*February 21, 2017*

**CAMBRIDGE**

Label the points from left to right: A,P,Q,M,B AP = 2x PB = 3x AQ = 3y QB = 4y PQ = 2 AP+PQ=AQ, so AQ-AP=PQ: 3y-2x = 2 PQ+QB=PB, so PB-QB=PQ: 3x-4y = 2 Solving that, we get y=2, so AB = 7y = 14

*February 21, 2017*

**value**

http://lmgtfy.com/?q=Concept+Of+Special+Interaction

*February 21, 2017*

**math**

twice as many hens can lay twice as many eggs in the same time.

*February 21, 2017*

**Data**

There are 15! ways to arrange the balloons. But, the 5 green balloons can be rearranged in 5! ways that appear the same. Same thing for the other colors. So, you end up with 15!/(5!6!4!) = 630,630 ways

*February 21, 2017*

**Pre Calculus 30**

#1. 5 choices for each digit. So, 5^4 #2. correct #3. 1 * 4^3 #4. 2^3 * 10^4 when repetitions are allowed, you get more choices...

*February 20, 2017*

**Quantitative Reasoning (MATH)**

false the yearly reduction amount decreases with a smaller remaining value.

*February 20, 2017*

**algebra**

25750 * 0.8^5

*February 20, 2017*

**Algebra**

right track, but you made a mistake right at the start: 6z^2 + 40z - 5 = 0 z = (-40±?(40^2+4*6*5))/12 = (-40±?(1600-120))/12 = (-40±?1480)/12 = (-40±2?370)/12 = (-20±?370)/6 z = -0.127 or -6.539

*February 20, 2017*

**Math**

just solve the normal way: C=T/70 +E/30 C + T/70 = E/30 (70C+T)/70 = E/30 E = 30(70C+T)/70 = 3/7 (70C+T) or, E = 30C + 3/7 T

*February 20, 2017*

**Algebra Word Problem**

(x-2)(x+2) = 9+12x x = 13 So, the numbers are 11,13,15

*February 20, 2017*

**math (precalc)**

complex values come in pairs (why?), so the roots are 3-4i, 3+4i, 5, 5 R(x) = (x-(3-4i))(x-(3+4i))(x-5)^2 = ((x-3)+4i)((x-3)-4i)(x-5)^2 = ((x-3)^2+4^2)(x-5)^2 = (x^2-6x+25)(x-5)^2 = x^4 - 16x^3 + 110x^2 - 400x + 625

*February 20, 2017*

**Pre Calculus 30**

#1 First consider all the ways where A&B are together. This is equivalent to permuting 6 students (AB,C,D,E,F,G): 6! = 720. But, we have to double this, since AB and BA are two possible ways that A&B can be together. There are 7! ways to permute the 7 students. 7! - 2*6! = 720...

*February 20, 2017*

**Algebra**

well, did you try the values, to see whether they work? 80*(-1.33)^2 - 96(-1.33) + 27 = 296.192 Hmmm. I'd say nope. So, too bad you didn't show your work... 80x2^ - 96x + 27 =0 Using the quadratic formula, since there are so many possible factors of 80 and 27, x = (96&...

*February 20, 2017*

**Algebra**

If you meant 2.1/(x+1) + 1 4/5 = 3/(10x) then x = -1±?(7/6) If you meant 2.1/(x+1) + 1 4/5 = 3/10 x (5±?77)/2

*February 20, 2017*

**math 1**

a = 2b-8, so (assuming the usual sloppiness with parentheses) 2b-8 = 2/(b-3) (b-4)(b-3) = 1 Now just solve the quadratic. I suspect a typo, just fyi.

*February 20, 2017*

**Algebra**

w(3w-2) = 65 5*13 = 65

*February 20, 2017*

**algebra**

so if the equations involve c and d, what are x and y? The first equation says c-3d = 27 so, c = 3d+27 Use that in the other equation: 4d+10c=120 first, divide by 2 so you can work with smaller numbers: 2d+5c = 60 Now, since c = 3d+27, that means 2d+5(3d+27) = 60 2d+15d+135 = ...

*February 20, 2017*

**Algebra - rats - and the t!**

L2 = (3,7,-11/3) - 4/9 (-3,-3,4)t = (3,7,-11/3) + 4/9 (3,3,-4)t

*February 20, 2017*

**Algebra - oops - lost the n**

L2 is (3,7,k) + n(-3,-3,4)t

*February 20, 2017*

**Algebra**

L1 is (4,2,-3) + (1,3,-2)t L2 is (3,7,k) + (-3,-3,4)t 4+t = 3-3n t 2+3t = 7-3n t 4+t-3 = 2+3t-7 t = 3 n = -4/9 Now we can see that -3-2t = k+4nt -3-2(3) = k+4(-4/9)(3) k = -11/3 L2 = (3,7,-11/3) - 4/9 (-3,-3,4) = (3,7,-11/3) + 4/9 (3,3,-4) at t=3, L1(3) = (4,2,-3) + 3(1,3,-2...

*February 20, 2017*

**physics**

well, it takes 0.4/1.7 = 0.235s to travel that distance. now use your usual equation of motion to find the vertical distance fallen in that time.

*February 20, 2017*

**Algebra/Math**

if it's 8% by weight, then .08 * 150 And the wording should be 150g of an 8% solution

*February 20, 2017*

**Math**

t = u-2 10t+u + 10u+t = 154 154 = 11*14 so t+u=14 the number is 68

*February 20, 2017*

**Math**

try again in English ...

*February 20, 2017*

**math**

review your basic trig functions. Draw a diagram. Note that tan? = 12/19 now you can find ?.

*February 20, 2017*

**Math**

this is just your classic work problem. You started out right, but then went off into the mists. 1/x = 1/40+1/60-1/80 1/x = 7/240 x = 240/7

*February 20, 2017*

**Math**

f = d^2 f+5 = 3(d+5)

*February 20, 2017*

**Math**

2(x+8) = 25 Solve for x, then use to get the area. = 8x

*February 20, 2017*

**math**

36+x = 3(4+x)

*February 20, 2017*

**value**

r^2 = 567/63 = 9 r = ±3 Now you can find a, and S6 = a(r^6-1)/(r-1)

*February 20, 2017*

**Science**

20/(60+20) = 1/4

*February 20, 2017*

**Chemistry**

.28 * 6.023 * 10^23 * 2

*February 20, 2017*

**Algebra**

well, 2 days = 48 hours, so ...

*February 20, 2017*

**Calculus**

#1 swap variables and solve for y: x = ?(3y-2) x^2 = 3y-2 y = (x^2+2)/3 now f(x) has domain: x >= 2/3 range: y >= 0 f^-1(x) has domain: x >= 0 range: y >= 2/3 because f(x) has only one branch #2 f(x) = ?[1,x] sin(t)/t dt I don't think you want f(x), because it ...

*February 19, 2017*

**Math 104**

5P2 = ?

*February 19, 2017*

**math**

(2,3) [2,3]

*February 19, 2017*

**Algebra2**

write a recursive formula for the sequence 5,18,31,44,57 then find the next term. My answer is a1=5,an=an-1+13 The next term would be 70.

*February 19, 2017*

**Calculus II**

google the topic and you will find many discussions and examples. For a region of uniform density, the center of mass is the same as the centroid.

*February 19, 2017*

**Pre-Calculus**

3 = 2.1 sin[(?/6)t - 5?/6] + 3.2 2.1 sin[(?/6)t - 5?/6] = -0.2 sin[(?/6)t - 5?/6] = -0.095238 (?/6)t - 5?/6 = -.0953826 (?/6)t = 2.522611 t = 4.8178 and of course, there is another solution

*February 19, 2017*

**Math**

9.50a + 5.50(148-a) = 1170.00

*February 19, 2017*

**Algebra2**

thank you

*February 19, 2017*

**Algebra2**

cd = k a constant. So, you want d such that 86d = 2*17

*February 19, 2017*

**Algebra2**

suppose c and d vary inversely and d=2 when c=17 write an equation that models that variation find d when c=68

*February 19, 2017*

**Algebra2**

note that xy = 10

*February 19, 2017*

**Algebra2**

Does the relation in the table represent direct variation, inverse variation, or neither? if it is direct or inverse variation, write an equation to represent the situation. Explain your answer x 5, 10, 15, 20 Y 2, 1, 2/3, 1/2

*February 19, 2017*

**MATH**

15/(10+15) = 3/5 = 60%

*February 19, 2017*

**Maths bearing**

use the law of cosines.

*February 19, 2017*

**Math**

use the law of cosines.

*February 19, 2017*

**Math**

I'd guess the same, if it's in the same circle ...

*February 19, 2017*