Sunday

September 21, 2014

September 21, 2014

Total # Posts: 25,114

**Physics**

You know that the initial height is the constant term. So, the building is 50m tall The ball hits the ground when the height is zero. So, just solve for t when h=0 I assume you want to know how long the ball is at least 55m above the ground. It is only at 50m for an instant. ...
*September 3, 2014*

**algebra**

√(2-w) = w^2 2-w = w^4 w^4+2w-2 = 0 The solutions to that are not trivial. So, assuming you meant √2 - w = w √2 = 2w 2 = 4w^2 w = ±1/√2 Better try again. Ignoring the first two lines, once you get to (w+2)(w-10) I'm sure you meant (w+2)(w-1...
*September 3, 2014*

**Math**

the questions posted here need to provide full context. using those three digits, the only number which is even and less than 300 is 254
*September 3, 2014*

**Math**

which "other" number?
*September 3, 2014*

**Honors Pre Calculus**

assuming the person starts at the wheel's lowest position when t=0, that means that f(t) will look something like f(t) = -cos(t) The radius is 25 feet, so that makes it f(t) = -25cos(t) The axle is 25+4=29 feet off the ground, so f(t) = 29-25cos(t) since cos(kt) has period...
*September 3, 2014*

**AP Physics**

116 km/hr * 1hr/3600s = 116/3600 km = 0.03222 km
*September 3, 2014*

**Science independent variable**

other things being equal, I'd say the temperature.
*September 3, 2014*

**algebra - repost**

I assume that x^ means x^2. Usually the caret requires a numeric exponent. After all, it could be cubed (x^3) or something else. Given that, we have (-2a^2 + 6ab^2 - 12a^2b^3) / -24ab The rest is very difficult to parse. Why not try reposting using clear notation as I did ...
*September 3, 2014*

**Math. Help Thanks!**

since the plane descends 100 feet as it travels 5000 feet, clearly the slope is -100/5000 = -0.02 so, since y=100 when x=0, y = 100-0.02x Note that when x=5000, y = 0, and we have touchdown.
*September 3, 2014*

**algebra 2**

Use a number with exponents. 4(x-1)^2 - 8 4(x^2-2x+1)-8 4x^2-8x+4-8 4x^2-8x-4 You must multiply the 4 by each term in the parentheses, not just the first one. 4(2+6) = 4*2 + 4*6 = 8+24 = 32 NOT 4(2+6) = 4*2+6 = 8+6 = 14 after all, 2+6=8, and 4*8 = 32
*September 3, 2014*

**11 Physics**

surely you have similar question that you can study. You know that the initial height is the constant term. So, the building is 50m tall The ball hits the ground when the height is zero. So, just solve for t when h=0 I assume you want to know how long the ball is at least 55m ...
*September 3, 2014*

**Algebra 2**

sorry (-3)^2 = (-3)(-3) = +9
*September 3, 2014*

**math**

If the 4th person invested y, then 1,000,000 + x + 2x + y = 1,100,000 But y is as much as the other three together, so y+y = 1,100,000 y = 550,000 I'm sure you can now find the other answers.
*September 3, 2014*

**Math**

You cannot locate √-15 on the real number line, because it is not a real number. √(94^3) = (√94)^3 = 9.695^3 = 911.364
*September 3, 2014*

**Math**

hint: 7 > 6 > 5
*September 3, 2014*

**math**

clearly each pack of wax has enough wax to make 2 candles (14/7 = 2). So, now can you figure how many candles can be made from 8 packs of wax?
*September 3, 2014*

**math**

1.50/3.75 = 0.4 = 40%
*September 3, 2014*

**Math**

First, you have to know how to factor numbers. 55 = 11*5 22 = 11*2 The only factor which is common to both is 11, so you have 11*5 + 11*2 = 11(5+2)
*September 3, 2014*

**maths**

If you draw a diagram, and mark the spot on the rim, you can draw a radius to the point. That radius will be the hypotenuse of a triangle, such that (r-1)^2 + (r-8)^2 = r^2 so, r=13 Hence, the diameter is 26 inches
*September 3, 2014*

**math**

Just to be clear, the number has to be at least 1.0 and less than 10. In interval notation that would be a number in [1.0,10.0)
*September 3, 2014*

**Physics**

original acceleration is a 1/2 at^2 = 37 v = at new acceleration is 2a since v = 2at, new time is (2.3v)/(2a) = 2.3at/2a = 1.15t new displacement is 1/2 (2a)*(1.15t)^2 = 2*1.15^2 at^2 = 5.29*37 = 195.73 m
*September 3, 2014*

**Math/chem**

you gave the formula: 25°C/7min = 25/7 °C/min
*September 3, 2014*

**mathematics1**

exposition is murky, but the result is correct.
*September 3, 2014*

**Math**

Well, is 11 between 30 and 40?
*September 3, 2014*

**calculus**

If this is a typical problem, then if he lands at a distance x from A, then the distance on water is √(x^2+5^2) and the distance on land is 6-x So, the time taken is t = √(x^2+25)/2 + (6-x)/4 dt/dx = x / 2√(x^2+25) - 1/4 = (2x-√(x^2+25)) / 4√(x^2+...
*September 3, 2014*

**math**

(7+16+20+12+8+18)/6 = ?
*September 3, 2014*

**calculus**

πr^2 h = 1000, so h = 1000/(πr^2) surface area is a = 2πr^2 + 2πrh = 2πr^2 + 2000/r da/dr = 4πr - 2000/r^2 = 4(πr^3 - 500)/r^2 da/dr=0 when r = ∛(500/π) thus, h = 100/∛(250π) Do the other along the same way.
*September 3, 2014*

**math**

#1. P(x) = x^2(x^2-9) = x^2(x-3)(x+3) x-intercepts are clearly 0,-3,3 P(0) = 0 for the y-intercept.
*September 3, 2014*

**math**

I'll do #1. You can try the others. 625 = 5^4, so f(x) = 1/5^x or 5^-x
*September 3, 2014*

**calculus**

As usual, draw a diagram. If x is the distance of the beam from the perpendicular line to the wall, then x/8 = tanθ x = 8tanθ So, dx/dt = 8sec^2θ dθ/dt When θ = π/6 (and that's pi, not pie!!) dx/dt = 8(4/3)(20*2π) = 1280π/3 m/s
*September 3, 2014*

**calculus**

Draw a diagram. d^2 = x^2+6^2 2d dd/dt = 2x dx/dt When d=10, x=8 Now plug in your values.
*September 3, 2014*

**calculus**

this is exactly analogous to your other problem with the revolving spotlight. See what you can do for it. Here, you are solving for dθ/dt instead of dx/dt.
*September 3, 2014*

**Root Words**

well, ambi- means two, so I guess that is more than one. I'd give my right arm to be ambidextrous!
*September 3, 2014*

**Algebra**

2√18 - 5√32 + 7√162 2√9√2 - 5√16√2 + 7√81√2 I think you can take it from here, no?
*September 3, 2014*

**Math**

I'd say any 5-digit number is greater than any 4-digit number.
*September 3, 2014*

**Math**

3% = 0.03 1/4 % = 0.0025 The proposed answer is incorrect, and so is yours. I think, however, that yours is a typo.
*September 3, 2014*

**math**

all polynomials have domain of all reals No polynomial has any kind of asymptote x^2-6x+5 = (x-3)^2 - 4 So you can find the vertex, which is a minimum. Since the vertex is farther away from x=-1 than it is from x=6, f(-1) > f(6) Since f(3-x) = f(3+x), it is evidently not 1:1.
*September 3, 2014*

**algebra**

If the dimensions are x and y, 2x+y=120 xy = 1350 Solve that to get x and y. There are two possible solutions. Note that the area is xy = x(120-2x) = 120x-2x^2 That's just a parabola. The vertex represents the maximum area.
*September 2, 2014*

**math**

for any color, just divide its number by the total to get the fraction desired.
*September 2, 2014*

**math**

have you no calculator? or, just type that into google for any calculations. You might want to use / for division.
*September 2, 2014*

**math**

of course it is. It's just a different proportion.
*September 2, 2014*

**math**

c = .026*60000 + .034*(89400-60000) = 2559.60
*September 2, 2014*

**Numerical Analysis**

consider the table for the two functions shown x f(x) g(x) -5 -350 0 -4 -176 1 -3 -72 2 -2 -20 3 -1 -2 4 0 0 5 1 4 6 2 28 7 3 90 8 4 208 9 5 400 10 It is clear that f(x)=g(x) somewhere in [1,2], since f(x)<g(x) when x<1 and f(x)>g(x) when x>2. Or, if you rearrange ...
*September 2, 2014*

**Math**

1.2^0 / 1.8^2 = 1/1.8^2 I suspect a typo, as we haven't really gone anywhere.
*September 2, 2014*

**Calculus**

If we call A's position at noon (0,0) then we have the positions of A and B after t hours A: (12t,0) B: (0,60-9t) The distance is thus d^2 = (60-9t)^2 + (12t)^2 = 225t^2-1080t+3600 At t=2, d=√(42^2+24^2)=√2340=48.37 So, at any time t, 2d dd/dt = 450t-1080 Now ...
*September 2, 2014*

**Math**

Perimeters are in the same ratios as the sides. You are unclear which rectangle is which, but I am assuming the larger one has perimeter 65, so the smaller one has perimeter 65 * 2/5 = 26 You are correct.
*September 2, 2014*

**Math**

Doesn't matter how many squares there are. The board is square, so each side is √11 = 3.3 cm must be a travel set. I suspect a typo.
*September 2, 2014*

**Calculus**

any line through (8,4) in the first quadrant is y-4 = m(x-8) So, if the line in question has slope m, the x-intercept is 8-(4/m) and the y-intercept is 4-8m So, L = √x^2+y^2 = √((8-(4/m))^2 + (4-8m)^2) = -4/m √((m^2+1)(2m-1)^2) Of course, there are other ways...
*September 2, 2014*

**algebra**

assuming any partial tiles are thrown away, the floor is 16 x 6 tiles So, 96 tiles are needed So, 5 boxes of 20 must be purchased, for $270
*September 2, 2014*

**Algebra 2**

If you will enter your expressions at wolframalpha, you can check your answers. Be sure to use enough parentheses so things are right. The web site will show you how it interprets your input.
*September 2, 2014*

**MATH**

start out with x x x x x minimum=5: 5 x x x x range=7: 5 x x x 12 median=9: 5 x 9 x 12 Now you can fill in any other values fitting in those intervals.
*September 2, 2014*

**math**

do you not have a calculator? Just add the numbers. Heck, you can even just enter 21456+9087 into google and it will calculate the sum.
*September 2, 2014*

**Algebra 2**

a - 2a/5 = 3 you have to multiply everything by 5: 5a - 2a = 15 You only multiplied the -2a/5 and the 3.
*September 2, 2014*

**Algebra1**

I assume you want the value for C. When you have an equation, as long as you do the same thing to each side, it remains true. So, C+4 = -24 You want C by itself, so if you subtract 4 from both sides, you have C+4-4 = -24-4 4-4=0, and of course, C+0 is just C, yo now you have C...
*September 2, 2014*

**math**

what's to explain? Write the facts in symbols: p^2 + (p+5)^2 = 625 Now just solve for p and find p+5
*September 2, 2014*

**Algebra**

$/ml is what we want. So, of course, that means that x $ / y ml = x/y $/ml = z $/ml z = x/y
*September 2, 2014*

**Algebra 1**

you are correct. Keeping the units around can help with this kind of problem. 15 gal * y mi/gal = x mi Note that the gal units cancel, leaving mi on both sides of the equation. If the units agree at the end, chances are good that your calculations are correct.
*September 2, 2014*

**Algebra 1**

just convert everything to decimal, and then the listing is easy, right? -√9 = -3 is a rational number. As such, it is, of course, also real.
*September 2, 2014*

**Algebra 2**

1: correct 2: (∞,3]U(5,11] all values less than or equal to 11, except those greater than 3 and less than or equal to 5.
*September 2, 2014*

**college algebra**

(x^2+x-6)/(x^2-4) = (x-2)(x+3) / (x-2)(x+2) Now divide that by (x+3) / 2(x+2) or, equivalently, multiply by 2(x+2)/(x+3) Lots of factors cancel.
*September 2, 2014*

**college algebra**

since x^2-x-12 = (x-4)(x+3), just multiply top and bottom by (x-4) x/(x+2) + (4x-3) / (x+2)(x-2) requires a common denominator of (x+2)(x-2). So, just multiply the first term top and bottom by (x-2) and then just add the numerators.
*September 2, 2014*

**math**

width: w length: w+4 2(w + w+4) = 84 Now just solve for w and calculate w+4.
*September 2, 2014*

**math**

c(1+.60) = 2000 Now just solve for c.
*September 2, 2014*

**math**

The side shortened least is longest, so (x-14)^2 + (x-13)^2 = (x-12)^2 Now, we all know that the 3-4-5 triangle is the only one with sides which are consecutive integers. So, x-14=3, making x=17. Solving the equation gives the same result.
*September 2, 2014*

**math**

what's to explain? Write the facts in symbols: p^2 + (p+5)^2 = 625 Now just solve for p and find p+5
*September 2, 2014*

**math**

(x+y)y = 70 (y-x)x = 12 now proceed
*September 2, 2014*

**algebra**

good work. Just for the future, recall that the domain of all polynomials is all real numbers.
*September 2, 2014*

**math**

221 = 13*17 you can use that to answer your question, rather murkily stated.
*September 2, 2014*

**Physics**

try C(x) = 4.00 + 0.40⌈10x⌉
*September 1, 2014*

**Geometry**

clearly, HJ+JK=HK, so x/4 + 3x-4 = 22 now just solve for x and evaluate the distances
*September 1, 2014*

**KIPP Believe**

divide the 740 into 20 equal parts of x each. There are thus 17x students and 3x faculty. So, 17x+3x=740 20x=740 x=37 So, there are 17*37 = 629 students 3*37 = 111 faculty
*September 1, 2014*

**Math Proof**

we want to show that |x1 + x2 + ... + xn| <= |x1| + |x2| + ... + |xn| Let's take n=3 We know that the inequality holds for n=2, so now we have |(x1+x2)+x3| <= |(x1+x2)| + |x3| But, we already know that |x1+x2| <= |x1|+|x2|, so we now have |x1+x2+x3| <= |x1|+|x2...
*September 1, 2014*

**Math**

Only the student can tell what was intended. We've provided two solutions, so our work is done here.
*September 1, 2014*

**Math**

Not quite 9^(1/2) = 3 but (n^4)^(1/2) = n^2 so the answer is 3n^2
*September 1, 2014*

**Math**

looks good to me.
*September 1, 2014*

**MA 112**

for a proportion, the two ratios must be equal So, a = a+b which can only happen if b=0. But, we cannot divide by zero, so a/b and (a+b)/b would both be undefined.
*September 1, 2014*

**math**

the numerator is a whole number, and it is multiplied by the other whole number.
*September 1, 2014*

**Math**

I get x^2+x-6 in the numerator, so better double-check your math.
*September 1, 2014*

**Math**

If there were x liters to start, then we have the following table: month water at end of month 0 x 1 x/2 + 1 2 (x/2 + 1)/2 + 1 = x/4 + 3/2 3 (x/4 + 3/2)/2 + 1 = x/8 + 7/4 ... n x/2^n + (2*2^n-2)/2^n = (x + 2*2^n-2)/2^n So, at the end of the 5th month there were (x+62)/32 = 4 x...
*September 1, 2014*

**math**

A. You can factor out 3/√x to get 3/√x (x^2-3x+2) 3/√x (x-1)(x-2) Or, if you don't want that extra 1/√x, now you can divide by it to get 3(√x - 1/√x)(x - 2) or 3(x-1)(√x - 2/√x) B. xy(x^2-4) xy(x-2)(x+2)
*September 1, 2014*

**math**

what is #x ?
*September 1, 2014*

**algerbra**

okay - your turn. Check the solutions to your other problems, and take a stab at it.
*September 1, 2014*

**algerbra**

Hint: graph the two lines. Note where they intersect.
*September 1, 2014*

**algerbra**

Using elimination, double the first equation and rearrange things a bit to get 6x+4y = 8 5x-4y = 3 Now add them up and it's clear that 11x = 11 and the rest is easy
*September 1, 2014*

**math**

If x at 10%, the rest (8900-x) at 9%, then calculate the interest: .10x + .09(8900-x) = 831 x = 3000
*September 1, 2014*

**math**

You need the Binomial Theorem: (a+b)^n = a^n + n a^(n-1) b + ... So, you have (3x-2)^3 = (3x)^3 - 3(3x)^2(2) + 3(3x)(2^2) - 2^3 = 27x^3 - 54x^2 + 36x - 8 (4x+5)^2 = (4x)^2 + 2(4x)(5) + 5^2 = 16x^2 + 40x + 25 Subtract them to get 27x^3 - 70x^2 - 4x - 33
*September 1, 2014*

**MA112**

Look at the common factors on both sides d(a-b) = b(c-d) What you want to do now is unclear, but go for it.
*September 1, 2014*

**math**

as with the other, just plug in the value for x: -2(4^2) + 5(4) - 10
*September 1, 2014*

**math**

That would be 3(-2)^2 - 2(-2) + 5 = 3(4)+4+4 = 20
*September 1, 2014*

**algerbra**

If there are no typos, then 8 = 6x-4 means x=2 So, that means that -3(2)-4y=2 y = -2
*September 1, 2014*

**algebra**

the equation for the height is h = 80 + 960t - 16t^2 As you recall, the vertex (maximum height) is at t = 960/32 = 30 Now just figure h(30)
*September 1, 2014*

**math packet**

(4)(-3/5)(10/-9) = -120/-45 = 8/3
*September 1, 2014*

**math**

one of my favorite sequences. Thanks for sharing.
*September 1, 2014*

**math**

just solve for p in -2000p² + 2000p + 1700 = 5000 The problem is that D has a maximum of 2200 when p = 0.5 I suspect a typo somewhere. Is D the monthly demand, or the weekly demand?
*September 1, 2014*

**math**

x^2 + (x+4)^2 = 20^2 Think of a scaled-up 3-4-5 triangle.
*September 1, 2014*

**Algebra 2**

Rearrange things a bit and you have 2m^2-8m + 6n^2-5n^2 2m(m-4) + n^2 It's kind of a strange problem; is there a typo in there somewhere?
*September 1, 2014*

**PRE CALC**

Just list the facts as given: u+f+t = 39 t = u-16 u+5f+20t = 208 Now just solve as usual
*August 31, 2014*

**math**

length=2w 2(w+2w) = 60 ...
*August 31, 2014*

**math**

If q quarts are to be drained, then .40(12-q) + 1.00q = .60(12) ...
*August 31, 2014*

**algebra**

S = P(1 - 0.25)
*August 31, 2014*

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