Friday
February 12, 2016

Posts by steve

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

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