# Posts by steve

Total # Posts: 52,274

**math**

2h15' + 1h30' = 3h45' = 3.75 or 3 3/4 hrs (3 3/4)/24 = 5/32 day

**Maths**

If the numbers are x1-x10, then the median is (x5 + x6)/2 = 10 Since the range was less than 4, that means that the numbers in order were 8 x x x 9 11 11 11 11 11 or 9 9 9 9 9 11 x x x 12 12 The median moved upward, so the even number was added on the top side, so it must have...

**math**

same thing, different numbers. You should recognize the hidden 3-4-5 right triangle in this one.

**math**

You have three sides of a right triangle. So the perimeter is 6.1 + 7.4 + ?(6.1^2+7.4^2) = 23.1 I have no idea what your 2nd post means.

**Differential equation**

since sec x is never zero, we can get rid of it. Now we have y' - x^2y^2 = 0 dy/y^2 = x^2 dx -1/y = 1/3 x^3 + c/3 y = -3/(x^3+c)

**Basic mathematics**

since sum(logs) = log(product) you have log(2*2^3/7^4) = log 16/2401

**Science**

well, you need A•B = 0 So, let B = A sin x >b>i - A cosx j

**Algebra**

what, no calculator? 5.57

**Maths**

(y - 3/2)^2 = (x + 9/4)

**Maths**

12x^3-8x^2+kx+18 = 0 If one root is a and the other is -a, then we have (with the third root being p) 12(x-a)(x+a)(x-p) = 12(x^2-a^2)(x-p) = 12x^3-12px^2-12a^2x+12a^2p So, we need -12p = -8 p = 2/3 12a^2p = 18 a^2 = 9/4 a = 3/2 k = -12a^2 = -27 check: (3x-2)(2x-3)(2x+3) = 12x^...

**Physics**

the round trip is 350 m. So, the speed of sound is 350m/s

**science**

the velocity changed by 30 m/s in 6 seconds. So, the acceleration a = -5 m/s^2 F = ma ...

**science**

PV=kT so, since T is constant, so is PV. You want P such that P*5 = 43*11 P = 94.6

**Economics**

How do falling prices affect supply? I'm having a hard time between either the supply curve moves to the left and the quantity demanded rises. I think the answer is that the quantity demanded rises.

**Math**

(4*2-2)^2/9+2 = 6

**math**

c*1.2 + 1.2 = c*1.4 c = 6

**Physics**

correct.

**algebra**

(x^2+1)^2 = x^4+2x^2+1 so, x^4+x^2+1 = (x^2+1)^2 - x^2 = (x^2+1+x)(x^2+1-x) No linear factors with rational coefficients.

**Science**

Use the 20N force as angle zero: <20,0> Then the 5N force is <-4.33,2.5> So, adding them up you get <15.67,2.5> Now just take the magnitude of that, and its direction angle ? has tan? = 2.5/15.67

**COMPUTER**

(x+y+z)/3 max(x,y,z) min(x,y,z) x+y+z

**Science**

what is the chemical composition of clay? and for polymers?

**Geometry Urgent Help plz!**

First, divide by 2. x^2-8x+18 = 0 the roots are provided by the quadratic formula: x = (8±?(8^2-(4*1*18))/2 You can see that they are complex because the discriminant is negative. So, there are no x-intercepts. The y-intercept is of course 36, since there, x=0. To find ...

**Math**

it is a family of lines through the center. See what you can do with that.

**maths**

If there are N animals in total, then there are N-55-65-50 pigs, assuming there are no other kinds of animals.

**Act sps**

p/2 (2a+(p-1)d) ------------------- = p^2/q^2 q/2 (2a+(q-1)d) 2a+pd-d ---------- = p/q 2a+qd-d q(2a+pd-d) = p(2a+qd-d) pqd + q(2a-d) = pqd + p(2a-d) (p-q)(2a-d) = 0 So, either p=q or d=2a

**maths**

First, you have to have the equation that relates chirp rate and temperature. Either you have been given that, or you can find it using google.

**Math probabilty**

looks good to me

**science**

all are matter compounds are formed of molecules molecules are formed of (usually different) atoms elements are formed of identical atoms

**math**

Let the ellipse be modeled by x^2/a^2 + y^2/b^2 = 1 Since the base has width 50, and the height is 28, we have b = 28 a = 25 and the ellipse is x^2/25^2 + y^2/28^2 = 1 When x=13, y=23.9

**Math hellppp**

correct. Although I'd have subtracted the beginning balance from the ending balance, showing that it had changed by $-77 (-12-65 = -77)during that month. But that was not one of the choices. D gives that answer, but the operations are bad.

**Math**

we have the piecewise cost function for weight w, c(w) = 2.50 for w <= 2 2.95 for 2 < x <= 3.5 3.40 for 3.5 < x <= 5 ... 2.50 + .45?(w-2)/1.5? So, now we want w such that 2.50 + .45?(w-2)/1.5? = 4.75 .45?(w-2)/1.5? = 2.25 ?(w-2)/1.5? = 5 4 < (w-2)/1.5 <= 5...

**Maths**

lim (x->1) (?(1+2x)-?(3x))/(?(3+x)-2?x) The fraction at x=1 is 0/0, so we have to try to resolve that. Multiplying by the conjugate of the denominator we have (?(1+2x)-?(3x))/(?(3+x)-2?x)) * (?(3+x)+2?x)/(?(3+x)+2?x) (?(1+2x)-?(3x))*(?(3+x)+2?x) / (3+x - 4x) as x->1 that...

**maths**

We have angle a in QII, and angle b in QI. So, sin a = 8/17 cos a = -15/17 sin b = 40/41 cos b = 9/41 sin(a+b) = sin a * cos b + cos a * sin b = (8/17)(9/41)+(-15/17)(40/41) = -528/697

**Math**

The distance fallen after t seconds is s(t) = 4.9t^2 meters So just plug in values for t. If you are interested in the distance fallen during the nth second, then just subtract the previous position. That distance d(t) is then just d(t) = s(t) - s(t-1)

**Math**

well, -6 is negative and |-8| is positive so, -6 < |-8| plot -5 and -8 on the number line. -5 is to the right of -8 so -5 > -8

**Language Arts need help fast!!**

all correct.

**Pakistan**

⌊ ⌋ ⌈ ⌉

**Pakistan**

⌊ ⌋

**Math**

If they used x gallons of 20% juice, then .20x + .70(20-x) = .40*20 x = 12 so, 12 of 20% and 8 of 70%

**ALGEBRA**

break-even is where cost = revenue. 43x+4576 = 65x ... P(x) = R(x)-C(x)

**ALGEBRA**

y=kx^2 y/x^2 is constant You want y such that y/11^2 = 3/9^2

**Math - eh?**

Ok. You have the polynomial 4x^3 - 12x^2 + 11x - 5 so what about it?

**Math**

correct

**Mathematics**

ar = 1 ar^4 = 8 Now divide and you get r^3 = 8 r = 2 so, a = 1/2 T8 = ar^7 = 2^6 = 64

**Math**

32/(8/2)+6=14

**pre-calculus**

A parabola has only one focus. You mean a hyperbola. Now, since the distances to the foci differ by 24, and the foci are 34 apart, you have a hyperbola with a = 12 c = 17 b = ?145 Since the center is at (-7,0) and the foci are on the line x = -7, the hyperbola is y^2/145 - (x+...

**science**

How long does it take to hit? h(t) = 45-4.9t^2 when is h=0? t = 3.03 seconds Now, what is h(2.03)?

**math**

Watch the amount of sugar and water: c(t) = (6+t)/(100+20t) Now you can answer the question.

**math**

x = ky^3/?z (x?z)/y^3 = k, a constant. So, you want x such that (x?4)/6^3 = (1372/3)(?9)/7^3 ...

**math**

If the width is w, then w(w+3)(w/7) = 242 ...

**ALGEBRA**

if the coefficients are real, then the complex roots occur in pairs. So, our polynomial is (x-2)(x-(4-3i))(x-(4+3i)) (x-2)((x-4)+3i)((x-4)-3i) (x-2)((x-4)^2+3^2) ...

**Maths**

?(x+?(x+?(x+...))) = 6 square both sides: x+?(x+?(x+?(x+...))) = 36 x = 36-?(x+?(x+?(x+...))) x = 36-6 = 30

**Math**

something wrong with my solution? Your question has not changed.*

**Math**

?((5+3)^2 + (-5-1)^2) = ?(8^2+6^2) = ?

**Maths**

1/4 + 3/6 = 3/4 So, 1/4 x = 2,50,000 (whatever that means...)

**math**

make that k2

**math**

r = k1v^2 + 2v^3

**Maths trigonometric**

8sinx-cosx = 4 8sinx = cosx+4 64sin^2x = cos^2x + 8cosx + 16 64-64cos^2x = cos^2x + 8cosx + 16 65cos^2x + 8cosx - 48 = 0 (5cosx-4)(13cosx+12) = 0 cosx = 4/5 or -12/13 so, sinx = 3/5 or 5/13

**algebra**

6^2 + h^2 = 12^2 so, what is h?

**Algebra**

14 hours = 50,400 seconds 855 minutes = 51,300 seconds yes, they are all about the same, but which is the smallest amount of time?

**Algebra**

I assume it means you need to multiply b^2 by something. Since b^8 = b^2 * b^6 b^6 goes into the box. Or, it might mean that b^2 is to be raised to a power. Since 8=2*4, (b^2)^4 = b^(2*4) = b^8 This appears to be just an exercise in working with properties of exponents.

**Maths**

I assume you mean log(384/5)+log(81/32)+3log(5/3)-log9 =log(384*81*125)/(5*32*27*9) =log(3888000/38880) =log 100 = 2

**Maths**

If you let u=3^x then the equation becomes (using parentheses to clarify matters) 9^(x+2) - 6*3^(x+1) = 0 9^2*9^x - 6*3*3^x = 0 81u^2-18u+1=0 (9u-1)^2 = 0 u = 1/9 So, 3^x = 1/9 = 3^-2 x = -2

**math**

Not even sure what the question is. If you are trying to write a fraction, then I'd guess at 9(4+2)/(3-1) = (9*6)/2 = 54/2 = 27 If that's wrong, then try rewriting it so we can tell what you want.

**Maths**

well, just plug in your numbers. (a) (1-h)^2 = 16 1-h = ±4 h = -3 or 5 Do (b) the same way.

**MATHS**

surely your text covers these topics. Offering complete courses is beyond the scope of this web site.

**Marh**

If there are x in the box, then 5/12 x = 3/8 x + 24 Multiply by 24 and you have 10x = 9x+576 x = 576

**pre algebra 1**

Assuming she only mowed the three lawns, then her total time was 1 3/4 + 2*(1 1/5) + 3/4 = 4 9/10 hours. That's 4:54, so subtracting that from 4:15, we have a start time of (using the 24-hour clock) 16:15 - 4:54 = 15:75 - 4:54 = 11:21 You are correct. Good job.

**Alegbra**

you should know that vertical angles are congruent. Each angle and its adjacent angle form a straight angle. So, the adjacent angles are 55°. 125+55 = 180 55+125 = 180 ...

**Math**

I think you're stuck. There's just no way to get things to just a product. According to wolframalpha, the integral is not elementary. http://www.wolframalpha.com/input/?i=integral+log(1-cotx)+dx

**Capleton**

a+5d = 2(a+2d) a+5d = 2a+4d a = d So, pick a first term, and use that for the difference. The sequence is thus a,2a,3a,4a,5a,6a,... 6a = 2*3a

**Math - oops**

Better go with Scott. I seem to have lost a factor of 2 somewhere. 7 hours is clearly not long enough for a smaller crew to do almost the whole thing.

**Math**

11h 40min = 700 minutes So, each man does 1/5600 of the job in a minute 8 men working for 60 minutes complete 8*60/5600 = 3/35 of the job. The remaining 6 men have to do 32/35 of the job, so it will take 8/6 as long as the full contingent of 8 men. The time is thus 8/6 * 32/35...

**Math**

The angles are 7x and 11x Now you know that 7x+11x = 180 Now git 'er done!

**Maths algebra**

This one has no rational roots. Your only hope is a numeric or graphical method.

**Math**

You have it backward. If the original population was x, then 1.9x = 16359 x = 16359/1.9 = 8610

**math**

4^2-2(3*5+1) = 16-2(16) = -16

**math**

if you mean 4 + 2^2 - 2(3*5+1) then that is 4+4-2(16) 8-32 -24 If that's not what you meant, then try using real math symbols (including parens as needed!) ...

**math**

The bearing is 360-?, where tan? = 7/24

**math**

let's assume there are 100 shirts, with a cost of $100 each. 17 are not sold: $0 18 are sold for $70 each: $1260 65 are sold for $150 each: $9750 total income: 11010 profit is thus 1010/10000 = 10.1%

**Maths**

If the slower's speed is s km/hr, then their combined speed of approach is s+2s = 3s So, since distance = speed * time, 3s * 3/2 = 2420

**Math**

it will be in grams the same as the atomic weight. All those words, to write 6.022*10^23 !!

**physic**

1st: 49t-4.9t^2 2nd: 49(t-3)-4.9(t-3)^2 So, when are the heights equal? 49t-4.9t^2 = 49(t-3)-4.9(t-3)^2 t=6.5 Now just plug that in to find the height.

**Math**

the area of the room is two side walls and two end walls, so 2*15*10 + 2*20*10 = 700 ft^2 The windows occupy 2*5*4=40 ft^2 So the cost is (700-40)ft^2 * Rs20/ft^2 = Rs 13200

**Calculus II**

I assume you know the chain rule, and that d/dx e^u = e^u du/dx Now, for some other base, such as 5, recall that 5 = e^ln5 So, 5^x = e^(ln5 x) d/dx 5^x = ln5 e^(ln5 x) = ln5 5^x So we arrive at the fact that d/dx a^u = ln(a) a^u du/dx and your result follows.

**math**

5+2x=35 2x=30 x=15

**Algebra**

4! = 24

**Algebra**

there are 4 choices for the 1st letter since that letter is used, there are only 3 choices for the 2nd letter. So, extending that logic, the number of possible passwords is 4*3*2 = 24

**math**

(15/20)/(4/10) = 15/8 = 1.875 or 87.5% increase

**trigonometry**

The sum-to-product formulas will make this just drop out easily.

**math**

come on. a 10% discount means that the new price is 90% as much (100 - 10 = 90) similarly, a 14 2/7% discount means the result is (100 - 14 2/7)% = 85 5/7%

**math**

85 5/7 %

**Maths**

the height is at 40 when t^2-14t+40 = 0 (t-4)(t-10) = 0 SO, it is above 40 for 6 seconds (between t=4 and t=10) x(x+7)/2 = 60 x^2+7x-120 = 0 (x+15)(x-8)=0 The triangle is the familiar 8-15-17 right triangle.

**Math222**

The domain of rational functions is all reals except where the denominator is zero. If your denominator is 5w, then only w=0 is excluded.

**Math**

check the ratios. 12/8.5 = 141% 16/11 = 145% So, use 141% so the width will fit. If you are really doing this on a machine, I think you'll find 141% on the menu.

**calculus**

you'd have to use some numeric integration technique to get an approximation.

**calculus**

That antiderivative is not expressible in elementary functions. It is an elliptic integral.

**Math**

If x is the larger angle, then x-28 + x = 140 ...

**algebra-math**

10^1^-x = (10^1)^-x 10^1 = 10 so, you have 10^-x = 10^4 so, x = -4

**singapore math**

k+y = 500 k+m = y+220 y+m = k+140 Or, in more standard format, k+m = 500 k+m-y = 220 -k+m+y = 140 These are easy to solve.