Sunday
January 22, 2017

Posts by STEVE

Total # Posts: 47,949

math
If you draw the diagram, you can see that you have a right triangle with 45° angles. So, the two legs are the same length: 60km.
November 30, 2016

Math
I think they want you to approximate it with the Taylor series, which involves y", y"', etc.
November 30, 2016

Math - good catch
thanks. leftover from a previous attempt.
November 30, 2016

Math
The volume of a spherical cap of radius r and height h (the water depth) is v = ?/3 h^2(3r-h) = ?/3 h^2(30-h) = ?/3 (30h^2 - h^3) dv/dt = ?(20h - h^2) dh/dt Now, when is h increasing most slowly? When the water surface area is greatest (since dv/dt is constant, and dv = a*dh) ...
November 30, 2016

cal
v = 10xy dv/dt = 10(y dx/dt + x dy/dt) So, using your numbers, dv/dt = 10(8(-4) + 6(2)) = -200 looks good to me.
November 30, 2016

cal
good call. So, rather than being where f' goes negative, it is where f' starts decreasing: where f" goes negative. That is, when the graph changes from concave up to concave down. Unfortunately, this graph starts out concave down, so the growth rate is always ...
November 30, 2016

cal
well, what does diminishing returns mean? Sales decrease while numbers increase. So, you want to find t for max N.
November 30, 2016

cal
f = 4x^3-21x^2+36x-4 f' = 12x^2 - 42x + 36 = 6(2x^2-7x+6) = 6(2x-3)(x-2) f" = 24x-42 = 6(4x-7) f is concave up for x > 7/4 f is decreasing for x in (3/2,2) So, both for x in (7/4,2) f has a max at x=3/2, so it cannot be concave up there.
November 30, 2016

math
what do you mean by one of the line of ax2+2hxy+by2=0 ?? That is a conic section, unless it's degenerate. In that case, you have (ax+c)(x+d)=0 ad+c = 2h cd = b Now work with the slopes of the lines, using the condition that one is twice the other.
November 30, 2016

Math
You sure there are no typos? I suspect you want (sinx+siny)/(cosx+cosy) Anyway, you can get things a bit simpler by taking the tan of both sides, since tan(arctan(x)) = x also, tan(x/2) = (1-cosx)/sinx
November 30, 2016

Math Logs
raise both sides as powers of 4, and you have, since 4^log_4(u) = u x+5 = 64(x-2) 63x = 133 x = 19/9
November 29, 2016

math
you want P where Pe^(.065*4) = 3000
November 29, 2016

precalculus
since (0,3) and (2,3) have the same y-value, the vertex is at x=1. So, (1,4) is the vertex, and we have y = a(x-1)^2 + 4 At x=0, a(1)+4 = 3 a = -1 y = -(x-1)^2 + 4 = -x^2+2x+3
November 29, 2016

precalculus
If you have to ask such a general question, you must not have read the relevant section in your text. So, you can start here: https://en.wikipedia.org/wiki/Row_echelon_form
November 29, 2016

precalculus
I get 2/x - 1/(x-1) + 2/(x-1)^2 what do you get?
November 29, 2016

algebra
m = (-5-(-10))/(-2-(-9)) = 5/7
November 29, 2016

Calc
what's the comma for? anyway, d/du arcsec(u) = 1/(x?(1-x^2)) the ?(x^2-4) I'm sure you can handle.
November 29, 2016

Finite Math
If there are x and y of A and B, then the constraints are 3x+4y <= 1000 6a+3b <= 22*60 The profit function is p(x,y) = 2.00x + 1.50y When you figure out the question you want to answer, this should help.
November 29, 2016

MATH PLZ HELP
After all the time you've spent posting this problem, don't you have any ideas? There just aren't that many ways to add at most three numbers to get 4: 1+1+2 1+2+1 2+1+1 ... Consider that she might have missed one or two throws.
November 29, 2016

Math
If the number is ab, then a.b = (a+b)/2 That is, a + b/10 = (a+b)/2 10a+b = 5a+5b 5a=4b Given the one-digit values of a and b, the number must be 45
November 29, 2016

math
so, for the 1st problem, x-2 = -2 8 = 2^3, so 2=8^(1/3) 4 = 2^2 so, 2^2 = (8^(1/3))^2 = 8^(2/3) That means 2/x = 2/3 and x=3
November 29, 2016

math
Font garbling, but (1/4)^(-2) = 16
November 29, 2016

math
27 = 3^3, so 3^(2x?1)= 1/(27^x) 3^(2x?1)= 1/3^(3x) 3^(2x-1) = 3^(-3x) 2x-1 = -3x 5x = 1 x = 1/5 25=5^2, so 5^(3x?8)·5^(4x) = 25^(2x) 5^(3x?8)·5^(4x) = 5^(4x) 3x-8+4x = 4x x = 8/3
November 29, 2016

6th grade math
(6 3/4)/6 = 1 3/24 = 1 1/8
November 29, 2016

Math
If you can do 5/6 and 3/4, then you can do 5/8. Just use a common denominator of 24 instead of 12.
November 29, 2016

math
true, 60+60=120, but there were 150 oranges.
November 29, 2016

Math
c + 5c = 24 solve for c, then get r, and then r-c
November 29, 2016

maths
clearly, 150/6 heaps so, how much profit per heap?
November 29, 2016

Pre-calc
as you know, sin(kx) and cos(kx) have period 2pi/k tan(kx) has period pi/k sin^2(x) = (1-cos(2x))/2 use a similar trick to find the period of tan^2(x) Looks like you need to review the basic info on trig functions.
November 29, 2016

Math
2*9 + 4*9 = (2+4)*9
November 29, 2016

Math
since the denominator is never zero, there is no vertical asymptote. as x gets huge, the fraction becomes tiny, so y=0 is the horizontal asymptote.
November 29, 2016

Math
well how many divisors of 24 are at least 4?
November 29, 2016

Correcting Math
65*1.07 + 65*.20 = ? Better try again. How did you arrive at your answer?
November 29, 2016

pre calc
see the post just below yours.
November 29, 2016

pre calc
don't forget your Algebra I! (2sin?+1)(sin?-1) = 0 now you can use your trig...
November 29, 2016

Linear Algebra
This is easiest with vectors, as discussed here: http://math.stackexchange.com/questions/371649/distance-of-a-3d-point-from-the-parametric-form-of-a-line Using the distance formula and calculus is a bit more involved.
November 29, 2016

Math
y = -3 x = 7 r = ?(9+49) = ?58 Now recall that sin? = y/r cos? = x/r tan? = y/x
November 29, 2016

Algebra2
8^3x=60 rewrite using the rules for exponents
November 29, 2016

math
3 * 1/6 = 3/6 = 1/2
November 29, 2016

pre calculus
see all the details here: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
November 29, 2016

Pre-Calculus
the larger of a and b is the major axis. In this case, the ellipse is vertically oriented. Think about it. When (x-2)=0, (y-4)=4 When (y-4)=0, (x-2)=3
November 29, 2016

maths
r = 1 - r cos? r(1+cos?) = 1 r = 1/(1+cos?) You should recognize this as a parabola. Now for the conversion. r = 1 - r cos? r^2 = (1 - r cos?)^2 x^2+y^2 = 1 - 2x + x^2 y^2 = 1-2x
November 29, 2016

Mathmatics Asap Please!!!!!
1+3+3 = 7 245/7 = 35 So, multiply the ratios by 35 to see what you need for 245kg of concrete: 35:105:105 Looks like there's enough for the mix.
November 29, 2016

Math
(12*71 + 92)/13 = 72 8/13 Note that 92 = 71 + 13+8
November 29, 2016

Math
Look at the changes in x and y x: up by 1 y: down by 5 so, start with y = -5x But, y(0) = -1, not 0, so y = -5x-1
November 29, 2016

Math
You want 13/2 as many cookies, so use 13/2 as much flour: (13/2) * (7 1/2) = 48 3/4 cups
November 29, 2016

precalculus
rearrange things a bit and you get 9x+18y = 17 6x+12y = 11 multiply the top by 2 and the bottom by 3 and you get 18x+36y = 34 18x+36y = 33 The two lines are parallel, so there are no solutions.
November 29, 2016

precalculus
note that if you multiply the first equation by 2, you get 4x+2y+16 So, the two equations describe the same line. Any solution to one is a solution to the other. There are infinitely many solutions.
November 29, 2016

Algebra 2
(1/6)/(1/3) = (1/6)/(2/6) = 1/2 1/6 of all the kids are scared of both.
November 29, 2016

pre calculus
You can do this. Just recall that (a) parallel lines -- same slope (b) intersecting lines -- different slopes (c) the same line -- just write it in two different ways
November 29, 2016

pre calculus
google is your friend. So is your math text.
November 29, 2016

maths
x * 6x = 5500
November 29, 2016

MATH
just multiply the dimensions. 1L = 1000 cm^3
November 29, 2016

precalculus
nope. Check the slopes. If the lines are parallel, then there is no solution.
November 29, 2016

Third Grade Math
won/total = 4/9
November 29, 2016

geometry
I see no equation. Maybe you mean r^2 cos? = cos(3?) r^2 cos? = 4cos^3(?) - 3cos? r^2 = 4cos^2? - 3 r^2 = 4(x/r)^2 - 3 x^2+y^2 = 4x^2/(x^2+y^2) - 3 (x^2+y^2)^2 + 3(x^2+y^2) - 4x^2 = 0 do with that what you will.
November 29, 2016

precalculs
just substitute y = 2x+2 into the first equation. You know a line intersects a parabola in at most two places.
November 29, 2016

precalculus
x = -y, so x^3 - 5x + x = 0 x^3-4x = 0 ...
November 29, 2016

precalculus
come on. This is Algebra I. What do you think is the answer? If nothing else, just plug in the values and see where they fit!
November 29, 2016

math
sure you do. Did you not read where it said Therefore, each factor equals 91? 3x-2 = 91 3x = 93 x = 31 It's hard to solve a problem if you don't read it!
November 29, 2016

Vectors and matrices
what's to do? Just draw the triangles. They even gave you the coordinates! Just to make sure they weren't lying, do the math: http://www.wolframalpha.com/input/?i=%7B%7B3,-1%7D,%7B5,-1%7D,%7B5,-4%7D%7D*%7B%7B1,0%7D,%7B0,-1%7D%7D
November 29, 2016

algebra
ever hear of y = mx+b It's called the "slope-intercept" form for a reason.
November 29, 2016

Algebra
well, if x is the number, what is 1/4 of the number? ...
November 29, 2016

physics
since each part has the same mass, conserving momentum is just conserving velocity: <0,8> + <-8,0> + <x,y> = 0 or, since the resultant momentum of the two known parts is NW, the 3rd part must go SE.
November 29, 2016

linear equations
reposting the same thing wastes everyone's time.
November 29, 2016

math
L = 2W 2(L+W):6L = 1:2 L+W/3L = 1/2 (2W+W)/(3*2W) = 1/2 3W/6W = 1/2 3/6 = 1/2 This is true for any value of W! I suspect the question has been mangled.
November 29, 2016

Maths quadratic equation
see related questions below
November 29, 2016

Math
google is your friend. You might want to start here: https://answers.yahoo.com/question/index?qid=20080427160136AACsLX6
November 29, 2016

Math
#1 has a typo you provide no pairs for 2,3,4,5 For #6, you know that x = y+3 So, y = x-3 I assume one of the graphs works for that. For the rest, work to isolate the variable #7 -4 = g+1 you want g all alone, so get rid of the 1 with subtraction -4-1 = g+1-1 -5 = g the others ...
November 29, 2016

Math
surely you can come up with something, at least to start with ...
November 29, 2016

math
I answered this when you were "somay" http://www.jiskha.com/display.cgi?id=1480393573
November 29, 2016

Math (Calculus) (Related Rates)
as we saw earlier, the distance z is z^2 = 1+x^2 z dz/dt = x dx/dt plugging in the numbers, z(3) = ?10, so ?10 dz/dt = 3 * 2 dz/dt = 6/?10 = 1.897 So, I guess you were right on that one. As for dz/dt when x gets large, consider that z^2 = 1+x^2 as x gets large, that is just z^...
November 29, 2016

Science
42
November 29, 2016

math
This one is really quite simple, if you understand what the mean and mode are. The mode is the most frequent score. Since there are only three scores, and the mode is 11, it must occur more than any other score. That is, 11 occurs twice. Since the mean is 9, the sum of the ...
November 28, 2016

math
that would be 5
November 28, 2016

math
the slope is the rate of sales, in cars/month. So, just use the numbers given: 13cars/3months = 13/3 cars/month The slope is 13/3
November 28, 2016

MATH
flour:sugar = (3/4):(3/5) = 5:4 so, a kg of flour costs 4/5 as much as a kg of sugar. That is, 5 kg of flour costs the same as 4 kg of sugar. So, the 4 kg of sugar cost half of the $14.80. That means a kg of sugar costs $3.70
November 28, 2016

math
since 9 and 4 are both perfect squares, try (3x-2)(3x-2).
November 28, 2016

Math
hint: 15-2 = 13
November 28, 2016

Math
yes. Since both points have 4 for a y-coordinate, the line is horizontal: y = 4
November 28, 2016

Math
x would represent a number. The width is twice the height. so, 2*3(x/3+5) = 90
November 28, 2016

algebra
guess again. 2*2-1 = 3 not -1 clearly you did not test your choice.
November 28, 2016

Math (Calculus) (Related Rates)
oops. I meant find dz/dt.
November 28, 2016

Math (Calculus) (Related Rates)
at a distance x, the length of rope (z) is z^2 = x^2+1 now just find dz/dx at x=3 it should be clear how z changes when x is large.
November 28, 2016

Math
.18x = 11800 love your capitalization and punctuation and spelling. <not>
November 28, 2016

maths
x + x+4 + 3x = 44
November 28, 2016

Math (please check my answer!!)
Nope. SSA does not work.
November 28, 2016

math
well, certainly both numbers must not exceed 20. So, how many pairs x,y with x,y <= 20 fit that?
November 28, 2016

Math
suppose I asked you to find w such that 50 = 5w what would you do? Divide by 5, right? So, divide by L: W = A/L
November 28, 2016

math
T10 = a+9d = 40 S10 = 10/2 (a+40) = 265 a = 13 so, d=3 S20 = 20/2 (2*13+19*3) = 830
November 28, 2016

math
what are the perfect squares less than 12?
November 28, 2016

Maths
7sin^2x - sinx cosx - 6 = 0 divide by cos^2 to get 7tan^2x - tanx - 6sec^2x = 0 7tan^2x - tanx - 6(1+tan^2x) = 0 tan^2x - tanx - 6 = 0 there's a typo, and any solutions must exclude x where cosx=0.
November 28, 2016

Math
both do, since there are no constants involved.
November 28, 2016

Math
If z>=0, 2+z > 1 -- z > -1 2-z <= -1 -- z >= 3 If z<0, 2-z > 1 -- z < 1 2+z <= -1 -- z <= -3 graph those on the number line, and you will find your answer. Be sure to check a few values to make sure they work, especially at the boundaries.
November 28, 2016

emt
?[0,1]?[0,1] (x^2+y^2+25)^(3/2) dx dy = 130.046 This is not a trivial task, since it involves trig substitutions. Anyway, look here to find the first indefinite integral. Plug in your two y-values, giving a similar integral involving only x. http://www.wolframalpha.com/input/?...
November 28, 2016

Math
42.42
November 28, 2016

Algebra
Clearly she must add 5 liters. So, to get the concentration, .14*2 + x*5 = .34*7 ...
November 28, 2016

Business Math
Hmmm. Too bad you didn't show your work... revenue = price * quantity. breakeven is when cost = revenue, so 3600+100x+2x^2 = x(500-2x) x = 10,90 maximum profit will be at the vertex of p = r-c, halfway between the roots: x=50
November 27, 2016

inverses
I don't mean the formula. I mean, in the original problem, what was the variable x defined to be? Answer that, and you have answered your problem.
November 27, 2016

inverses
well, what does x represent?
November 27, 2016

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