Friday

February 12, 2016
Total # Posts: 37,611

**math**

r^3 = 4375/35 = 125, so r=5 Now use that as you need to.
*January 5, 2016*

**Math**

LCM(8,7)=56, so the ages are in the ratios of 35:56:24 Since those three numbers add up to 115, they are also the ages.
*January 5, 2016*

**Math**

well, geez -- how about, um, substituting? You see that x = y-6, so substitute that into the other equation and you can then find y: y = 6-3(y-6) ...
*January 5, 2016*

**Math 11**

of what?
*January 5, 2016*

**Calculus**

y=1, and x=2 Bogus limits. Fix one or the other. In any case, the radius is 10-y and v = pi r^2 h
*January 4, 2016*

**calculus**

My bad. Using discs, the integral is v = ∫[0,1] π(R^2-r^2) dy where r = 1-√(1-y) and R = 1+√(1-y) v = ∫[0,1] π((1+√(1-y))^2-(1-√(1-y))^2) dy = ∫[0,1] 4π√(1-y) dy = 8π/3
*January 4, 2016*

**calculus**

Why don't you show your work? Using shells, try v = ∫[0,2] 2πrh dx where r = x and h=y=2x-x^2 v = ∫[0,2] 2πx(2x-x^2) dx = 8π/3 Using washers, we have v = ∫[0,1] π(R^2-r^2) dy where r = 1-√(1-y^2) and R = 1+√(1-y^2) v = &#...
*January 4, 2016*

**Calculus**

You're right. The boundaries are not clear to me either. http://www.wolframalpha.com/input/?i=plot+y%3D2sinxcosx%2C+y%3D2cosx
*January 4, 2016*

**Trigonomentry help plz thanks**

This is a challenge analytically, but using the graph it is easy: http://www.wolframalpha.com/input/?i=%28cosx%29^7%2B%28sinx%29^4%3D1 Coming up with the solutions -π/2, 0, π/2 is easy, but showing there are no others is tough.
*January 4, 2016*

**Bionomial expansion help agn #thanks**

The third term is C(6,2)(√x)^4(1/√y)^2 = 15x^2/y
*January 4, 2016*

**Calculus help plz i do not no it at all**

I seriously doubt it. Take a look at how wolframalpha interprets that: http://www.wolframalpha.com/input/?i=integral+x%E2%88%9A%282%2B3%E2%88%9C%28x^3%29%2F%28x^6%E2%88%9Ax%29%29 Maybe you can play around with your syntax till you get what you want.
*January 4, 2016*

**Calculus help plz i do not no it at all**

Do you mean x√(2+3∜(x^3)/(x^6√x))? I doubt it. How about some clear text with matched parentheses? If there are higher roots, just spell them out, as cuberoot(x), 4throot(x), etc.
*January 4, 2016*

**Word problem help plz**

oops. 85-41=44 Still no joy.
*January 4, 2016*

**Word problem help plz**

I guess by inverted you mean the digits are switched. So, if the father's age is xy and the son's age is ab, then we have 10x+y+10a+b=99 10a+b+10y+x=72 10x+y-(10b+a)=28 http://www.wolframalpha.com/input/?i=solve+10x%2By%2B10a%2Bb%3D99%2C+10a%2Bb%2B10y%2Bx%3D72%2C+10x%...
*January 4, 2016*

**Word problem help plz**

what is an "inverted age"?
*January 4, 2016*

**Algebra 1**

there is no solution to the given system.
*January 4, 2016*

**Algebra**

slope is 7, so y-0 = 7(x-0) or, y=7x
*January 4, 2016*

**ALEGEBRA 1**

clearly, y=y now substitute in the two different definitions. Draw the two lines. The solution is where they intersect.
*January 4, 2016*

**Math Complicated**

no, clearly it does not. The long bar over the sum means to evaluate everything under the bar, and then take the root of the result. Think of the long bar as a set of parentheses, as I showed above.
*January 4, 2016*

**Math Complicated**

No long lines online, but you can use parentheses: √(5 + 8 +24) = √37 since 5+8+24=37
*January 4, 2016*

**Math**

just add powers in products, and subtract in divisions: (6x^4)(4y^2) / [(3x^2)(16y)] = (6*4)/(3*16) * x^(4-2) * y^(2-1) = 1/2 x^2 y = x^2y/2
*January 4, 2016*

**Math**

Not sure what you mean by "make 3/5 to 21/25" 3/5 * 7/5 = 21/5
*January 4, 2016*

**Geometry**

yes, it is a "normal" trapezoid; it just means that its two non-parallel sides are not the same length. So, all you have to do is show that two of the sides of ABCD are parallel, and the others, not. Clearly, AB and CD are parallel, since they have the same slope. So...
*January 4, 2016*

**physics**

well, F = ma = 4200(3 + 10)
*January 4, 2016*

**geometry**

the surface area is just the sum of the two ends and the curved side. a = 2πr^2 + 2πrh = 2π*4*(4+12) Now just evaluate that on your calculator.
*January 4, 2016*

**Math**

whenever you have problems like this, draw a right triangle. In this case, you want a triangle with one angle x. If the sides are a,b,c with b opposite angle x, and c the hypotenuse, then sin(x) = b/c Now, the angle whose cosine is b/c is the other acute angle of the triangle...
*January 4, 2016*

**Maths**

3 times as many men means it takes 1/3 as long, right?
*January 4, 2016*

**Mathematics**

take a look at the point-slope form of a line, and you will see that yours is y-35 = 3/4 (x-40)
*January 4, 2016*

**engineering maths. need answer asap**

just conserve momentum before and after the collision. You then have 15*10 + 30*5 = (15+30)v
*January 4, 2016*

**math**

so, what's the difference between the area of a 12x12 square and a circle of diameter 12?
*January 4, 2016*

**Conversions**

all you have to do is add 273.15 to get the K temperature. That's not going to make much difference in 10^9 degrees.
*January 3, 2016*

**Geometry**

well, since all opposite sides of any parallelogram are parallel, it's not clear just what your question is.
*January 3, 2016*

**Math**

the answer cannot be 0,0. You are asked to find the coordinates of the vertices. Since the center of dilation is (0,0) and the scale factor is 4, just multiply all of the coordinates by 4.
*January 3, 2016*

**math**

since distance=speed*time, 2x = 4(x-4) x = 8 so, the distance is 2*8 = 16 miles each way
*January 3, 2016*

**math**

One way is to find the point on 13x+4y=32 which is at a distance of 4 from the line 3x+4y=28. Since the distance from (h,k) to ax+by+c=0 is |ah+bk+c|/√(a^2+b^2) and we know that k = (32-13h)/4, we have |3h+32-13h+28|/5 = 4 |-10h+60| = 20 h = 4 or 8 so, k = -5 or -18 ...
*January 3, 2016*

**Math**

correct. If you got that, I think your work must have been fine. It's due to the chain rule.
*January 3, 2016*

**Math**

domain of all exponentials is (-∞,∞) Range of a^x is (0,∞), so I'm sure you can adjust that as needed here. you know that the domain of √x is [0,∞), so now you just have to adjust to make sure that x-2 >= 0. As for the range, just recall ...
*January 3, 2016*

**Math**

Oops. I meant (c)
*January 3, 2016*

**Math**

Looks like (d) to me no constant difference no constant ratio
*January 3, 2016*

**Math**

beginning: at rest during: in circular motion end: at rest
*January 3, 2016*

**Math**

Ivan: 4.25+1.25m Vicky: 5.75+0.75m I+V: 4.25+1.25m+5.75+.75m = 10.00+2.00m = 2(5+m)
*January 3, 2016*

**Math**

well, you know that x=y-6, so, um, uh, substitute? y = 6-3(y-6) y=6 Now you can find x.
*January 3, 2016*

**mathematics**

well, 1.5 * 115 = 172.5 but that's not the $130 you say she has. Better fix up the question and post it as yo received it.
*January 3, 2016*

**Maths equation plz help urgently**

If you mean 10^x = 100, then clearly x=2, since 100=10*10 = 10^2
*January 3, 2016*

**trigonometry**

Since there are two angles of 55°, the vertex angle is 70°. So, each of the two matching sides has length 54/cos55° Now you can add up the sides to get the perimeter.
*January 3, 2016*

**algebra**

you have a point and a slope (2), so use the point-slope form: y-6 = 2(x-0) Now just rearrange the terms as needed.
*January 3, 2016*

**MATHS**

21 15/20 - 18 4/20 = ?
*January 3, 2016*

**maths lit, egd, civil , business studies**

maybe teach one of them?
*January 3, 2016*

**Math**

6 9/12 - 2 4/12 - 1 9/12 = ?
*January 3, 2016*

**math 7th grade connections**

d+g/h = 35+19/6 = 35+3.17 = 38.17 (d+g)/h = (35+19)/6 = 54/6 = 9 59+13n = 59+13*44 = 631 Something tells me you have trouble with the order of operations.
*January 3, 2016*

**Science**

Draw a triangle. If the plane's speed due north is v, then 60^2 + v^2 = 240 direction θ such that sinθ = 60/240
*January 3, 2016*

**geometry**

You need to explain a bit more how the angles and sides are positioned.
*January 2, 2016*

**MATHS**

Clearly the large cube is 6x6x6. So, how many 2x2x2 cubes is that?
*January 2, 2016*

**Algebra**

what? No ideas? The fee is constant.
*January 2, 2016*

**Calculus help plz**

I suspect a typo. Wolframalpha indicates that it cannot be done with elementary functions: http://www.wolframalpha.com/input/?i=integral+%28%28x%2B1%29%2F%28x-1%29%29^%281%2F3%29%2F%28x%2B1%29dx If I got it wrong, and only the (x+1) is in the cube root, it can then be done, ...
*January 2, 2016*

**math**

naturally, 1-.2 = .8
*January 2, 2016*

**physcis**

of course, you have to watch the units (2π√80 cm)/(10 m/s^2) mixes up cm and m. Convert cm to meters by (2π√80 cm)(1m/100cm)/(10 m/s^2) = π√80/500 s^2 = 0.056 s^2 An odd quantity, s^2
*January 1, 2016*

**math- HELP!**

Oww! My bad! Should have caught my typo. 26π*200 in/min The ridiculous speed of less than 1/2 inch per minute should have caught your eye!
*January 1, 2016*

**math- HELP!**

26π in/rev * 200rev/min = 26π/200 in/min w is not 200. It is 200*2π radians/min
*January 1, 2016*

**Math**

You have the equations x+y=−2 y=13x+2 You know it is a 2-D graph The lines intersect at (-2/7,-12/7), so none of the choices listing a different intersection can be right. That leaves only (A). Now you just have to check to see whether the lines pass through the named ...
*January 1, 2016*

**Math**

so, did you graph it? Which choice matches your findings?
*January 1, 2016*

**Math**

(x + 1/x)^2 = 3 x^2 + 2 + 1/x^2 = 3 x^4 - x^2 + 1 = 0 x = ±i^(1/3), ±i^(5/3) using i^(1/3), we have x^37 = i^12 i^(1/3) = i^(1/3) x^31 = i^10 i^(1/3) = -i^(1/3) x^47 = i^15 i^(2/3) = -i i^(2/3) x^26 = i^8 i^(2/3) = i^(2/3) x^63 = i^21 = i x^9 = i^3 = -i Looks ...
*January 1, 2016*

**Math**

5^3x = 65 3x log5 = log65 3x = log65/log5 x = log65/3log5 I assume you meant 2^(2x+3) = 80 (2x+3)log2 = log80 2x+3 = log80/log2 x = (log80/log2 - 3)/2
*January 1, 2016*

**science**

google is your friend. 1st hit solved the problem.
*January 1, 2016*

**computer programming**

use the function to calculate the nth fib #, and return its value. Then loop for p=1..5 and print each value returned.
*January 1, 2016*

**Calculus need help**

do you mean (x+x^3)/y or x + x^3/y ? It makes a difference
*January 1, 2016*

**Math**

(a) clearly, a = (5x+15)(31-2x) (b) I think you can graph a parabola (c) values for zero area (d) use what you know about parabolas (e) ditto (f) since this is a real-world situation, negative lengths are meaningless. So, D = [-3,31/2] R = [0,<value at vertex>]
*January 1, 2016*

**MATHS**

see related questions below.
*December 31, 2015*

**Algebra**

well, 1/12 of w is w/12 so, what's 4 more than that?
*December 31, 2015*

**Math**

y = (7/8)^x log(y) = x log(7/8) ... y=log12x 10^y = 12x ... and similarly for the last one.
*December 31, 2015*

**Calculus**

Each slice of water is a rectangle. Its length is 10. If the water has depth y, then the width of the rectangle is √(1 - (1-y)^2) = √(2y-y^2) Now you have to figure the water's depth (h), and the height to pump each slice of water is 2-y. So, you have to ...
*December 31, 2015*

**Math**

car 1 is 1/6 * 65 = 65/6 miles ahead when car 2 starts. car 2 is going 10 mi/hr faster, so it will take (65/6)/10 = 65/60 hr to catch up. In other words, 65 minutes.
*December 31, 2015*

**Math**

just add powers for multipliers, subtract for divisors. f^3 g^-1 / f^2g^3 = f^(3-2) g^(-1-3) = f^1 g^-4 = f/g^4 (k^−2m^3n)×(kmn^5)÷(k^− 1m^2 n) = k^(-2+1-(-1)) m^(3+1-2) n^(1+5-1) = k^0 m^2 n^5 = m^2 n^5
*December 31, 2015*

**Math**

domain is all reals since 2^x > 0, 2^x-7 > -7, so the range is (-7,∞) I expect you can do the intercepts, right? Just set x=0 or y=0.
*December 31, 2015*

**Maths need help trigonomentery**

If the two radii are x and y, then π(x^2+y^2) = 29π/2 2π(x+y) = 10π factoring out the π, x^2+y^2 = 29/2 x+y = 5 Now you should be able to solve for x and y
*December 31, 2015*

**Geometry**

check out the angle bisector theorem.
*December 31, 2015*

**Operating system**

Just a gut feeling, I'd say it is not. The MRU page is likely to be the next page accessed, don't you think? Swapping it out is likely to be a waste of time.
*December 31, 2015*

**geometry**

CD will be parallel to AB, and of the same length. B-A = (2,2) So, D = C+(2,2) = (0,8) or C-(2,2) = (-4,4)
*December 31, 2015*

**math**

r = (a+b-c)/2 = 2
*December 31, 2015*

**Maths**

If the digits are t and u, then the value of the number is 10t+u. So, we have t+u=7 10u+t = 10t+u-9 Now just solve for t and u. You can do this without any algebra. I mean, how many pairs of numbers add up to 7? Just try them.
*December 31, 2015*

**computer**

read x,y if y == x*x then { yes } else { no }
*December 31, 2015*

**maths**

well, 6000 is 5/12 std above the mean. Look that up in your Z table. You can play around with this stuff at http://davidmlane.com/hyperstat/z_table.html
*December 31, 2015*

**Math**

you want to solve for t in 400t - 16t^2 = 2400 Then find the difference in the two times.
*December 31, 2015*

**probability**

well, using brute force, just list the ways you could pair up the socks. How many of those ways fit the requirements?
*December 30, 2015*

**Physics**

for inital velocity v, we have h(t) = vt-(g/2)t^2 This reaches a max height at t=v/g, and h(v/g) = v(v/g) - (g/2)(v/g)^2 = v^2/g - v^2/2g = v^2/2g So, we see that max height is directly proportional to v^2 So, double v, and you quadruple the max height. M does not matter, as ...
*December 30, 2015*

**Math**

In the first G.P. the numbers are a, ar, ar^2 To form the A.P., the differences are constant, so ar-a = ar^2-4 - ar Then, forming a new G.P. with constant ratio, we have (ar-1)/a = (ar^2-4-1)/(ar-1) Solving for a and r, we have a=1, r=3 or a = 1/9, r=7 The 1st G.P. is 1, 3, 9 ...
*December 30, 2015*

**physics(optics)**

nothing.
*December 30, 2015*

**Physics**

well, the acceleration is 4 m/s^2, and F=ma.
*December 30, 2015*

**Math advanced function**

Since a quadratic can two solutions, and a trig function can two solutions per period, I expect that 4 solutions is as many as you can have. For example, sin^2(x) = 1/4 has 4 solutions in one period. sin^2(x) = 2 has none, sin^2(x) = 1 has two Maybe you can find some with an ...
*December 30, 2015*

**Math**

Draw the triangles. Recall that the sides are in the ratio 1:√3:2 Label the longest hypotenuse, and then work down to get the desired leg's size. I get 6. I am assuming there are only two triangles.
*December 29, 2015*

**Physics**

check your previous post.
*December 29, 2015*

**maths**

In that case, recall that one log is the reciprocal of the other. So, If you let u = log3x, then you have u + 1/u = 5/2 2u^2 - 5u + 2 = 0 (2u-1)(u-2) = 0 u = 1/2 or u=2 Thus, u = √3 or 9
*December 29, 2015*

**maths**

Or, did you mean log3x+logx3 = 2.5 ?
*December 29, 2015*

**math**

If the lawn has side x meters, then lawn area: x^2 total area: (x+1)^2 path area: (x+1)^2-x^2 = 2x+1 So, we have x^2 = 2x+1 + 23 Now just find x.
*December 29, 2015*

**Physics**

original: <0,-398> wind: <-104,0> result: <-104,-398> = 411 at 195° or 411 at S15°W To get back on course, you just need to negate the wind. So, you want <x,y> + <-104,0> = <0,-398> <x,y> = <104,-398> or 411 at S15°E
*December 29, 2015*

**stats**

9 dancers total 5 warmed and had no injuries (W & ~I) You want ~W or I = ~(W & ~I) So, your probability is 1 - 5/9 = 4/9
*December 29, 2015*

**maths**

well, 3000 is 20 times 150, so it will take 20 times as long, right?
*December 29, 2015*

**Maths**

which two factors of 15 differ by 2?
*December 29, 2015*

**Factorize**

a^3-b^3 = (a-b)(a^2+ab+b^2) so, x^3 - (x+y)^3 = (x-(x+y))(x^2+x(x+y)+(x+y)^2) Now just simplify that.
*December 29, 2015*

**Maths**

well, just substitute: √(1-x^2) = √(1-sin^2 θ) Now, what is your most basic trig identity?
*December 29, 2015*