Saturday
April 30, 2016

Posts by Steve

Total # Posts: 40,032

math
3/4 * x = 2/5 (380-x) + 32 x = 160 Kelvin gets 160, spends 120 Winnie gets 220, spends 88
April 20, 2016

Maths
12000L / (150L/min) = 80 min
April 20, 2016

Maths
yes. That is the way they are defined.
April 20, 2016

math
42
April 20, 2016

Calculus (easy)
(2√2,5π/4)
April 20, 2016

Calculus
(i) v = ∫[0,1] π(R^2-r^2) dy where R^2=2-y^2 and r=y^2 (ii) v = ∫[0,1] 2πrh dy where r=y and h=√(2-y^2)-y^2
April 20, 2016

science
To conserve water, an animal's kidneys can pump ions across cell membranes, allowing water to move by
April 19, 2016

Trigonometry
well, since tan60° = √3, 2θ-34 = 60
April 19, 2016

trig
to find A, sinA/63 = sin53°/50 having C and A, B is easy since A+B+C=180. get b using law of sines or law of cosines.
April 19, 2016

Polar, Cylindrical, and Spherical Coordinates
good. I thought it would make sense if you looked at it a while.
April 19, 2016

Polar, Cylindrical, and Spherical Coordinates
no help from my earlier comments? http://www.jiskha.com/display.cgi?id=1461018078
April 19, 2016

math
15 km
April 19, 2016

Math
20/(3 1/2) = 20/(7/2) = 20*2/7 = 40/7 = 5 5/7 so, 5 pieces, plus 5/7 of a piece left over. Since one piece is 7/2 feet, 5/7 * 7/2 = 5/2 = 2 1/2 feet left over. Or, 20 - 5(3 1/2) = 20 - 17 1/2 = 2 1/2 ft left over
April 19, 2016

Math
if there are x liters of 25% juice, then there are (20-x) of 55% juice. So, .25x + .55(20-x) = .21(20)
April 19, 2016

geometry
with θ in radians, rθ = 8/5 since c=12, r = 12/(2π) = 6/π θ = (8/5)(π/6) = 4π/15 = 48°
April 19, 2016

Algebra. NEED HELP ASAP PLEASE
what is x when y=0? the intercept indicates how long it will take for sales of such cell phones to stop.
April 19, 2016

math
2^16 = 65536
April 19, 2016

Calculus
clearly e^(-6/√n) -> e^(-6/∞) = e^0 = 1
April 19, 2016

Pre-Calc
clearly -1 is not a solution, since log(-1) is not real. log3(x(x-2)) = 1 x^2-2x = 3 x^2-2x-3 = 0 (x-3)(x+1) = 0 so, yes, x=3 is a solution, but -1 is extraneous.
April 19, 2016

math
At distance x, the shadow has length s, so s/6 = (s+x)/8 s/6 = s/8 + x/8 4s = 3s+3x s = 3x ds/dt = 3 dx/dt so, the length of the shadow shrinks at a constant rate of 9 ft/s.
April 19, 2016

geomtry
have to know the linear scale. Areas scale by that value squared.
April 19, 2016

math
clearly, also 97 all the other prime factors must be less than 97, since they are factors of numbers from 1 to 96.
April 19, 2016

math
20 x^2 y But I suspect a typo.
April 19, 2016

Geometry
since AB=AC, ABC is isosceles, and AN, besides being an altitude, is another median, like CM. The medians intersect 2/3 of the way from each vertex to the opposite side. The altitude AN forms two 5-12-13 right triangles, so AN=12, and AX=8.
April 19, 2016

Algebra
Since there are two = signs, I'll assume the second one is a +. Then we have 7 – 5(2 – x) = –(x – 8) + 11/6 7 - 10 + 5x = -x + 8 + 11/6 5x+x = 8 + 11/6 - 7 + 10 6x = 77/6 x = 77/36 I expect there's a typo I misread, so just fix it and then follow ...
April 19, 2016

math
w(5w-23) = 42 Now solve for w. Or, consider that two factors of 42 are 6 and 7.
April 19, 2016

Math
since the angles add to 180°, angle F is 72°. Using the law of sines, DF/sin72° = 24/sin45° x = 32.28 So, did you just guess at A?
April 19, 2016

Math
-4+12 /(-3) 10+3(-2) -4 -4 10 - 6 I suspect another symbol is missing: ...(-3) ? 10 ... Maybe also after the +12 If so, fill it in and continue.
April 19, 2016

Math
or, once you have A and C, B = 180-(A+C)
April 19, 2016

Math
tan(θ)/ sec(θ) − cos(θ) = tanθ * cosθ - cosθ = sinθ/cosθ * cosθ - cosθ = sinθ - cosθ
April 19, 2016

math algebra
1.05x = 18165
April 19, 2016

Math
57 = 3s
April 19, 2016

Algebra
no, 45 = 9*5 9! = 9*8*7*6*5*4*3*2*1 = 362880 How ever did you decide on A?
April 19, 2016

Math
rubbish There's a 25% chance of not growing. So, P(3 not) = 7C3 .25^3 .75^4 = 0.17
April 19, 2016

Further maths
a = 3d d = 8 so, a=24 and the AP is 24,32,40,...
April 19, 2016

Physics
recall that F = k(q1 q2)/d^2 now just plug and chug, after looking up k.
April 19, 2016

Math
d = 40074/pi
April 19, 2016

Math
I don't see a question, but the expected value E = 3(3/34) + 2(10/34) - 1(21/34) = 4/17 = $0.24
April 19, 2016

math
C
April 19, 2016

Calculus
there are many handy Riemann um calculators online, such as http://www.emathhelp.net/calculators/calculus-2/riemann-sum-calculator/
April 19, 2016

Calculus (Urgent, please)
The curves intersect at (±1.25,1.56) using symmetry, the area is a = 2∫[0,1.25] √(4-x^2) - x^2 dx = 3.35
April 19, 2016

Math
7/10 + 7/20 = 21/20 So, 1/20 prefer both. But how can someone prefer two days?
April 19, 2016

math
your files are not available to us online.
April 19, 2016

math
9999 * 100
April 19, 2016

Math
y = x+12 3y-5x = 20
April 19, 2016

Math No!
nope. He spent that money, and 700 was left. So, x - x/4 - 2x/5 = 700 x = 2000 1/4 of 2000 = 500 2/5 of 2000 = 800 So, he spent 1300, leaving 700
April 19, 2016

Math
since there is no question, I see little point in hinting at answers.
April 19, 2016

science
try google
April 19, 2016

maths
not sure what "to s" means, but a suitable trapezoid has only two right angles.
April 19, 2016

math
last I checked, there were 435 reps. and that's there, not their!
April 19, 2016

Maths
√(12+6√3) + √(12-6√3) 12+6√3 = 9 + 6√3 + 3 = (3+√3)^2 so, you have just 3+√3 + 3-√3 = 6
April 19, 2016

advanced calculus
The central arm's endpoints are a circle of radius 100: x = 100cosθ y = 100sinθ At θ=0, the arm is horizontal. So, assuming the wheel's boarding position is also at θ=0, and its angle is relative to the central arm, the boarding location's ...
April 19, 2016

Calculus
The region is just a square of side √2, with its center at (2,1). Using the Theorem of Pappus, the surface area is thus the perimeter of the square times the distance traveled by its centroid: a = 4√2 * 2π = 8π√2 Doing it using the usual definition...
April 19, 2016

math
you really need to work on your text formatting.
April 19, 2016

Calculus I
you can verify this at http://www.wolframalpha.com/input/?i=plot+y%3D1%2F12+x^3,+y%3D4x-32%2F3,+0%3C%3Dx%3C%3D6
April 19, 2016

Calculus I
f(x) is a constant, so the slope is zero everywhere!!
April 19, 2016

Pre-Calc
logb(4) sqrt((x^7 y^2)/(z^4)) well, I'm not sure what logb(4) has to do with it, but log(a^n) = n*log(a) so, log(√(x^7y^2/z^4)) = 1/2 (7logx + 2logy - 4logz) = 7/2 logx + logy - 2logz regardless of the base.
April 18, 2016

Math college grade 12
well, 0.8^t = 1/300 t log0.8 = -log300 ...
April 18, 2016

Math-Trig
the diagonals bisect each other, and are perpendicular to each other. So, draw the figure, and note the four right triangles formed.
April 18, 2016

geomatry
(-1-(-5))/(-4-2) = 4/-6 = -2/3
April 18, 2016

math
you can't. If all you have is the volume, it could be a cube of side ∛10 or, a brick with sides 1 x 2 x 5 2 x 2 x 2.5 4 x 2 x 1.25 10 x 5 x 0.2 etc.
April 18, 2016

Calculus
(ds)^2 = (dx/dt)^2 + (dy/dt)^2 = (-sint + sint + tcost)^2 + (cost - cost + tsint)^2 = t^2cos^2(t) + t^2sin^2(t) = t^2 so, ds = dt that's pretty easy to integrate, right? Hmmm. I missed that ^2 hanging out there. Is y(t) = sint - t(cost)^2 or y(t) = sint - tcos(t^2)? In ...
April 18, 2016

Solid Mensuration
google is your friend. You might start here: http://www.contracosta.edu/legacycontent/math/stararea.htm
April 18, 2016

Math
5n+25q = 460 n+q = 28 now just solve for n and q.
April 18, 2016

Geometry
looks good to me.
April 18, 2016

Geometry
at the fold. unless you fold it the other way, and then it would still be the 50-yd line...
April 18, 2016

Math
If the dimensions are x and y, then if the change fraction was r, xy = 300 (xr)(yr) = 363 xyr^2 = 363 r^2 = 363/300 r = 1.1 so, a 10% increase was used.
April 18, 2016

math
c+t=30 3c = 2t
April 18, 2016

Math
h(t) = 1 + vt - 16t^2 max height is reached at t = v/32, so 1 + v(v/32) - 16(v/32)^2 = 35 v = 8√34 h(t) = 1 + 8√34 t - 16t^2 h=0 at t=2.94 v(t) = 8√34 - 32t, so when h=0, v = 8√34 - 32(2.94) = -47.43 ft/s
April 18, 2016

Trigonometry
well, geez, just solve the equation. r = v^2sin2θ/g 1/32 1200^2sin(2θ) = 3000 sin2θ = (32*3000)/1200^2 = 1/15 Of course, there are two solutions, since sinθ is positive in [0,pi]. But you want the minimum value.
April 18, 2016

Math
clearly the answer cannot be 1, since that would mean you always get tails or roll less than 4. there are 12 possible outcomes, easy to list them. 1/2 give tails 1/2 * 3/6 = 1/4 gives heads and n<4. 1/2 + 1/4 = 3/4 or, consider P(heads & n>=4) = 1/2 * 1/2 = 1/4 you want ...
April 18, 2016

math
1.00 = 100% decrease by 17% leaves 83% = 0.83
April 18, 2016

Precalculus
consider the circle r = 2cosθ that is (x-1)^2+y^2 = 1 clearly r = 2scosθ is just a scaled up version of that. (x - s)^2 + y^2 = s^2 r = 2scos(θ+t) is just a rotated version, turned through angle t. Since t can be anything from 0 to 2pi, the center of our circle ...
April 18, 2016

Math
(3cm)^3 * 6 = 27*6 cm^3 = 162 cm^3
April 18, 2016

Math
that will be 1/2 + 1/2 * 1/6 = 1/2 + 1/12 = 7/12 you want P(heads OR (tails and n=3))
April 18, 2016

math
(x,y) -> (-x,y) so, just change the sign of the x-coordinates.
April 18, 2016

Math
parallel? I think not. They are the same line. Any solution to one also fits the other.
April 18, 2016

Trig
or island B
April 18, 2016

Math
width=w length=2w-5 perimeter: 2(w+l) = 2(w+2w-5) = 2(3w-5) = 6w-15 area: wl = w(2w-5) = 2w^2-10w that wasn't so hard, now, was it?
April 18, 2016

math
nope. sqrt(256) = 16 A is all irrational. and that's pi, not pie!
April 18, 2016

Trig
no cosine. the hypotenuse does not come into the calculation.
April 18, 2016

Trig
you draw a picture fer pete's sake! Then, having reviewed your basic trig functions, you will see that the height h is found from h/60 = cot35°
April 18, 2016

math
cube: 28^3 pyramid: (1/3)(28^2)(16) now just add 'em up
April 18, 2016

math
If train B's speed is x, then A's is x-6 Since time = distance/speed, 200/(x-6) = 230/x
April 18, 2016

Calculus
where did the 0 come from? also you cannot have cos and cos in f'.
April 18, 2016

Calculus
well, it's easy enough to see whether an answer is right. If f^-1(2) = x, then f(x) = 2 clearly not. It appears you want (f^-1)'(2) f'(x) = 7-3sinx+2cosx f'(2) = -3sin2+2cos2 (f^-1)'(2) = 1/f'(2)
April 18, 2016

calculus
nasty, until you note that f(x) = (x+1)/(2x+1) f'(x) = -1/(2x+1)^2
April 18, 2016

Math
see related questions below.
April 18, 2016

Trigonometry Help please
z^n = r^n cis(nθ)
April 18, 2016

math calculus
y = x^(2/3)(10-x) = 10x^(2/3) - x^(5/3) y' = (20/3)x^(-1/3) - (5/3)x^(2/3) = 5/3 (4-x)/x^(1/3) y'=0 when x=4 y increases when y'>0, or x<4 see the graph and info at http://www.wolframalpha.com/input/?i=x^%282%2F3%29%2810-x%29
April 18, 2016

Algebra
well, you need 3x+4 >= 0 at x=-4/3, y=-5, its minimum value.
April 18, 2016

math
You have seriously garbled the question. It looks like a straightforward law of cosines problem. The distance d is found using d^2 = 12^2+5^2 - 2*12*5 cos37°
April 18, 2016

Math
the 2nd equation is 0.04176x + 0.01782y = 0.01034 then since you have y, 0.04176x + 0.01782(0.4276-x) = 0.01034 0.02394x = 0.0027202 x = 0.1136
April 18, 2016

Algebra
make that Range = [-5,∞)
April 18, 2016

Algebra
I assume you mean y = 2√(3x+4)-5 the domain of √x is x >= 0, so here you must have 3x+4 >= 0 x >= -4/3 That is, the domain is [-4/3,∞) Since √(3x+4)=0 at x=-4/3, the range is [5,∞)
April 18, 2016

math
9Am, of course. But the watch shows 9:00AM - 0:2*48 = 7:24 AM
April 18, 2016

math p.s. is very hard
when x changes by 1, y changes by -5. So, the slope is -5 y = -5x + b Since when x=0, y=-1, y = -5x-1
April 18, 2016

Algerbra (Please help ASAP)
and F as well.
April 18, 2016

algebra
1/b - 1/a = 1/c - 1/b b-a = (c-4)-b b/a = (c-3)/b I get c=12
April 18, 2016

math- algebra 2
20000 * 1.05^13
April 18, 2016

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