Tuesday
June 28, 2016

Posts by Steve

Total # Posts: 41,497

Math
just adjust the scale by a factor of 12: 1:228
May 11, 2016

Math/Precal
5C0(-4x)^5(-3)^0 + 5C1(-4x)^2(-3)^1 + 5C2(-4x)^3(-3)^2 = -1024x^5 -3840x^4 - 5760x^3
May 11, 2016

Maths
the angles add to 180, so the largest angle is 95 now use the law of sines to find x, the shortest side: x/sin37 = 267/sin95
May 11, 2016

Math
((9y-3)-(3y-7))/2 = 3y+2
May 11, 2016

Math
you are correct; the discriminant is positive.
May 11, 2016

Math
well, what is 1qt:1gal ? same ratio, right?
May 11, 2016

Differential Calculus
did you actually draw an isosceles triangle with a base of 10? A = 1/2 bh Let's not forget the basics now that we're in calculus!
May 11, 2016

Differential Calculus
we have the height h is h = 5tanθ a = 5h = 25tanθ da/dt = 25sec^2θ dθ/dt Now just plug in your numbers (in radians!)
May 11, 2016

Calculus
we have tanθ = h/4 sec^2θ dθ/dt = 1/4 dh/dt Now just plug in your numbers.
May 11, 2016

Maths
of course, this is a stupid question, since the tank and the jug are in gallons, who cares how many liters it is? 1 gallon = 231 in^3
May 11, 2016

Maths
rather than convert each dimension, let's just convert in^3 to cm^3 at the end: 11.8*19.7*15.7 * 2.54^3 cm^3 Note that he holy has to fill 1/2 the tank. Now you know how many liters, just convert that to gallons to find how many trips it will take.
May 11, 2016

Calculus
if the beam touches the ground x feet from the wall, and touches the building at a height of y feet, then x/3.375 = (x+8)/y y = (27/8)(x+8)/x The length z of the beam is z^2 = x^2+y^2 = x^2 + ((27/8)(x+8)/x)^2 Crank through the algebra, and you find that dz/dx=0 at x≈5....
May 11, 2016

Calculus
because that's the definition of tan(a): opposite/adjacent. Did you draw a diagram of the setup? That's the first step to all of these problems.
May 11, 2016

Calculus
If the angles to the bottom and top are a and b, then from a distance x we have tan(a) = 8/x tan(b) = 18/x We want the angle c=b-a, so c = arctan(18/x)-arctan(8/x) dc/dx = 10(144-x^2)/((x^2+8^2)(x^2+18^2)) dc/dx=0 at x=12
May 11, 2016

MATH
what, given the numbers, you can't write an expression that adds them up? Fie on thee!
May 11, 2016

math
you know that sin(x) has period 2pi. So, since x/2 changes half as fast, it has period 4pi: y = 2sin(x/2)
May 11, 2016

Algebra
You have mangled your expressions. I cannot parse them at all. I suggest you go to wolframalpha.com and type in your expressions. Watch to see how they get interpreted, and use parentheses till you get what you expect.
May 11, 2016

Pre algebra
clearly B is wrong, since 1/3 (-3) - 8 = -1-8 = -9 Note that y changes by -3 when x changes by 1. So, the slope is -3. So, check A and D to see which works.
May 11, 2016

Math
x^3 is the 4th term. So 5C4 2^2 x^3 = 10*4*x^3 = 40x^3
May 11, 2016

7th Math
of the 36 possible outcomes, only one is 6,6
May 11, 2016

MATHS
on each draw, the probability is easy to get. Just multiply them together, as the draws are independent events.
May 11, 2016

MATH
2/7 * 5/7
May 11, 2016

math
j=4d j+4 = 3(d+4) now just solve for j and d.
May 11, 2016

Math
amateur
May 11, 2016

Math
B looks good to me although technically there is a factor of 100 missing in there, since the answer is really 35%, not 35.
May 11, 2016

MATH
again? Just add up how many even outcomes there are, and divide by the number of spins. Same problem as before, just different numbers.
May 11, 2016

Math
right again.
May 11, 2016

Math
The major axis has length 12, and the center is midway between the two points given, or (1,2) (x-1)^2/16 + (y-2)^2/36 = 1
May 11, 2016

math
clearly, 102/300
May 11, 2016

Math
correct
May 11, 2016

Simple Question
military pay is generally rather low, at least in the beginning.
May 11, 2016

math
(a) h/126 = tan46° (b) (i) 72/x = tan46° (ii) 72/z = sin46°
May 11, 2016

math
just use the definition of n! 4! = 4*3*2*1
May 11, 2016

Math
you don't say which two lines, but I infer that they are x = -1 and x=1. The region is symmetric about the y-axis, so we can just double the area from 0 to 1. using discs, v = 2∫[0,1] π(R^2-r^2) dx where R=e^x and r=e^-x v = 2∫[0,1] π(e^2x - e^-2x) dx...
May 11, 2016

Math
well, what are 4-3 -2-0 -1-2 ??
May 11, 2016

network programing
adobe brick? cowhide? more likely lead paint or asbestos But not sure what that has to do with network programming...
May 11, 2016

math
well, looking at the graphs, it looks like -2 <= x <= 2 checking, if we call them f(x)+g(x) >= h(x), then f(-2) = 20√5 g(-2) = 0 f(2) = 0 g(2) = 20 h(-2) = 28 h(2) = 20 so, f(-2)+g(-2) >= h(-2) f(2) + g(2) >= h(2) Clearly we need x >= -2 for √(x+2...
May 11, 2016

Calculus
As Reiny says, a rectangle whose base goes from 0 to x has area a = xy = xe^(-x^2) da/dx = (1-2x^2) e^(-x^2) so there is a max at x = 1/√2 That is assuming, of course that the rectangle has its base on the x-axis. It might be possible that a rotated rectangle could be ...
May 11, 2016

Math
each roll gives 10 possible outcomes, so there are 10^4 events. I ain't gonna list them, but the list starts and ends with 1 1 1 1 1 1 1 1 ... 10 10 10 9 10 10 10 10
May 11, 2016

maths
well, every second the velocity increases by 0.2 m/s. So how much is that after 10 seconds?
May 11, 2016

Algebra
no, that is 6.08 x 10^-7 power Move the decimal point to the right for positive powers (multiplying by 10)
May 11, 2016

math
the diagonal is 90√2=127.28 feet, so the mound is not in the center of the diamond (63.64 ft from home). So, you can't use the Pythagorean Theorem here. Instead, use the law of cosines: x^2 = 60.5^2 + 90^2 - 2*60.5*90*cos45° x = 63.72 feet
May 11, 2016

math
just use what you know about geometric sequences: S14 = 25(1.1^14-1)/(1.14-1) = 499.55 km
May 10, 2016

Math
your answer is good, but there are other systems with 3 sets of axes which do the same job. try googling your question. You will see discussions of the other characteristics of the system.
May 10, 2016

Math
since 1 qt is 1/4 of a gallon, you can go 1/4 as far: 9mi/qt or, using the proper units, get the gallons to cancel: 36 mi/gal * 1gal/4qt = 36/4 mi/qt
May 10, 2016

Math
18^2 + h^2 = 82^2
May 10, 2016

math: permutations
correct.
May 10, 2016

Math help ASAP please
well, plug in t=7. -16*49 + 96*7 = -112 You must be guessing, not calculating. When the ball hits the ground, its height is zero, right? Note that h(t) = -16t(t-6) Now, when is h=0?
May 10, 2016

Math
come on. You want to land in one of 10 equal areas. The chance is 1/2? Try again.
May 10, 2016

Math
well, 54+36 = 90
May 10, 2016

math
Also, sometimes someone comes in and just dumps a lot of homework questions with no indication they plan to do any work on their own. And some questions are so garbled or silly they cannot be deciphered, or do not deserve an answer.
May 10, 2016

math
usually because no one among the tutors has the particular expertise needed at the time.
May 10, 2016

maths
because sin(x) is positive in that domain. Your answer is incomplete because you only mentioned QII.
May 10, 2016

Algebra
so, now it's down to A or D. Do the math...
May 10, 2016

Algebra
you have 5(2x^3+6x-4) / -5(x-5) = -(2x^3+6x-4)/(x-5) a little synthetic division shows that it does not divide evenly. I suspect a typo. However, it is clear that only B or C could work, even after the typos is fixed.
May 10, 2016

Geometry
Let M be the midpoint of AD. Then you have two right triangles BMA and DMC where you know the hypotenuse and one leg. Use the Pythagorean Theorem to find BM and MC.
May 10, 2016

Nutz
–0.5(4 + x) = –1.3 -2.0 - 0.5x = -1.3 -0.5x = 0.7 ...
May 10, 2016

math
man - have you ever seen the graphs? google is your friend, as is your textbook. both are conic sections, but a parabola has eccentricity = 1 an ellipse has eccentricity < 1
May 10, 2016

MATH HELP PLEASE
#1 nope. you missed a minus sign #2 could be right, if there was supposed to be a +5 in there #3 nope #4 nope #5 nope. you added, but you should have subtracted. If I ask how much bigger 6 is than 2, you don't add 6+2. #6 nope. you add exponents when multiplying powers. ...
May 10, 2016

Algebra
collect like terms and you get 8x^2+8x-3
May 10, 2016

Math Please Help
#1 ok #2 nope. You picked the chance of getting a vowel, but that's not what they asked. #3 ok #4 ok #5 ok
May 10, 2016

Analytic Geometry
you know it has a double root at x=0 so, the graph is tangent to the x-axis at (0,0) The graph crosses the x-axis at x=4 y is positive for large negative values of x, so the graph comes down from the left, touches (0,0), goes back up and crosses at (4,0) on its way down to the...
May 10, 2016

calculus
Hmmm. I misspoke. The average value is ∫[0,2] V(t) dt --------------------      2-0 = 0.3010
May 10, 2016

calculus
That would just be (V(2)-V(0))/(2-0) = 0.6554/2 = 0.3277
May 10, 2016

Linear Algebra - urgent!
google is your friend. You could start here: http://math.stackexchange.com/questions/986859/why-is-deta-lambda-i-lambda-cn-when-a-cin-0
May 10, 2016

Algebra 2
not quite sure what you mean by t time is on 120 sec From what you said, it appears that h = at^2 + 35000 But, from the two data given, it looks like h(120) = 35000
May 10, 2016

Math
well, jeez - look at the 7 row. How many 8's are there?
May 10, 2016

Maths grade 12
of course , if siny = 0, then we have cosy = 1 or -1. You can try those for other solutions.
May 10, 2016

Math (please help)
the box is 8" long, so the paper has to be long enough to wrap around the ends. I'd say (D)
May 10, 2016

math
center is at (-6,5) so (x+6)^2/a^2 + (y-5)^2/b^2 = 1 The semi-major axis is vertical,and of length 13. c^2 = a^2-b^2 165 = 169-4, so b=2 (x+6)^2/4 + (y-5)^2/169 = 1 see http://www.wolframalpha.com/input/?i=ellipse+%28x%2B6%29^2%2F4+%2B+%28y-5%29^2%2F169+%3D+1
May 10, 2016

maths
recall that the product of the roots will be f/1 If f is prime, then the only possible rational roots will be ±1, ±f Since f and -f cannot both be roots (why?) there can be at most 3 rational roots. Furthermore, since f is positive (why?), -1 cannot be a root, ...
May 10, 2016

calculus sir damon help me or steve
recall your half-angle formulas for hyperbolic functions: sinh(x/2) = √((coshx-1)/2) so, √(coshx-1) = √2sinh(x/2) dx/√(coshx-1) = 1/√2 csch(x/2) dx now just use your standard form for integrating csch(u)
May 10, 2016

math
k = .6l l = .6m m-140 = l now just find k+l+m
May 10, 2016

math
a+b=108 3a/4 + (2/5)(b+a/4) = (3/5)(b+a/4) now just solve for b.
May 10, 2016

geometry and trig
If the cylinders are similar, then the ratio of volumes is (10/4)^3 as much, or 15.625 lbs = 250 oz how did you get 137pi? I suspect something is left unsaid here, as none of the choices seems right.
May 10, 2016

algebra 1
well, he is 1.75 std above the mean, or 28 + 1.75 * 8
May 10, 2016

Mayh
1/2 of 1/2 = 1/4
May 10, 2016

math: probability
wrong.
May 10, 2016

math: probability
correct, if you replace the first card before drawing the second.
May 9, 2016

Algebra
ignoring the mysterious comma, 3fg(f^2+5f-4) = 3f^3g + 15f^2g - 12fg
May 9, 2016

math
sounds like a rectangle to me.
May 9, 2016

Science
the same
May 9, 2016

calculus
(lnx)/(x) x^(lnx-1) = x^(lnx)/x
May 9, 2016

calculus
Is the lnx/x suppose to be (lnx)/(x) or ln(x/x)?
May 9, 2016

calculus
I don't understand how you went from y' = lnx x^(lnx -1) + lnx x^lnx (1/x) to lnx/x x^lnx + lnx/x x^lnx. Where did the -1 go? May you please explain?
May 9, 2016

calculus
recall that d/dx x^n = n x^(n-1) d/dx a^x = lna a^x so, if y = u^v, y' = v u^(v-1) u' + lnu u^v v' Here you have u = x v = lnx So, y = x^lnx y' = lnx x^(lnx -1) + lnx x^lnx (1/x) = lnx/x x^lnx + lnx/x x^lnx = 2lnx/x x^lnx or, do it like this y = x^lnx lny = lnx...
May 9, 2016

calculus
Find dy/dx. y = x^ln x, x > 0
May 9, 2016

Math
well, geez - did you plug in the values? y(0) = 5, so it will end in +5 1^2 = 1, so y = -x^2 + 5 so, yes, B is the answer.
May 9, 2016

Algebra
y = kxz 4 = k*4*1 k = 1 y = xz
May 9, 2016

Algebra
If the point is x miles from NYC, then since time = distance/speed, (3458-x)/(850+50) = x/(850-50)
May 9, 2016

math
Assuming you actually replace the 1st ball before drawing the 2nd, then the chance of drawing a green ball in at least one of the draws is the complement of drawing no green ball either time. The chance of no green ball twice in a row is 50/70 * 50/70 = 35/49 So, the chance of...
May 9, 2016

Differentiation
again?
May 9, 2016

maths
2(70 + 80+20) - 2(70+80) = 2(20) = 40 m or, 20m on each long side...
May 9, 2016

Differentiation
A = 3t^2 + 7 dA/dt = 6t now plug in t=5
May 9, 2016

Math
q = d+8 n = d-5
May 9, 2016

Algebra
Since time = distance/speed, 66/(r+7) = 24/r
May 9, 2016

math
1 + 6/16 = 1 + 3/8 = 1 3/8 can't see how that would have caused you any trouble...
May 9, 2016

physics
mv1 = <0,-144> mv2 = <-270/√2, 270/√2> add the vectors and then change back to direction and magnitude.
May 9, 2016

functions
A little division shows that 6x^3-ax^2+bx+c / (x+4) has a remainder of -16a-4b+c-384 6x^3-ax^2+bx+c/(x^2-4) has a remainder of (b+24)x+c-4a So, -16a-4b+c-384 = -220 b+24 = 23 c-4a = -26 solve those and you get f(x) = 6x^3 + 31/2 x^2 - x - 88 You can verify the remainders for ...
May 9, 2016

MATHEMATICS
geez, impatient much?
May 9, 2016

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