Saturday
December 10, 2016

Posts by Steve

Total # Posts: 47,042

Math
At height h, h/4 = tan? 1/4 dh/dt = sec^2? d?/dt So, plug in your numbers and find dh/dt
December 5, 2016

Geometry
Assuming the three points lie on a single line, then since the slope is constant, (5-2)/(4-1) = (2-0)/(1-x) x = -1 Note that x changes by the same amount as y between points. Since y changed by -2, from 2 to 0, x changed by -2, from 1 to -1.
December 5, 2016

precalculus
x^2/a^2 + y^2/b^2 = 1 The semi-axis lengths are a and b. Naturally, the larger is the major. If it's a, the ellipse lies horizontally. If it's b, the ellipse stands up, because the major axis is vertical.
December 5, 2016

geometry
since PB is the bisector, the other two angles are equal. x+2 = 2x-6 solve for x, and then you can find your angle.
December 5, 2016

Calc
f(x)=2sinx-sin2x f(7pi) = 0 f(8pi) = 0 f(x) is continuous. So, it satisfies the MVT. In fact, it satisfies Rolle's Theorem. (f(8pi)-f(7pi))/(8pi-7pi) = 0 f'(x) = 2cosx - 2cos(2x) = 2cosx - 2(2cos^2x-1) = -4cos^2x + 2cosx + 2 = -2(2cos^2x - cosx - 1) = -2(2cosx+1)(cosx-...
December 5, 2016

Calc
see your other post
December 5, 2016

precalculus
replace y by (y-k) and x by (x-h) Better review your text where it talks about translation of functions.
December 5, 2016

precalculus
you know what y=ax^2 is, right? Now shift it by (h,k)
December 5, 2016

Math
You can always multiply by 1 without changing things. A conversion factor is just a way of writing 1 so that units cancel as desired. Suppose you want to convert lbs to kg. You know that 2.2lb = 1kg So, 2.2lb/1kg = 1 1kg/2.2lb = 1 So, if you want to convert kg to lbs, you can ...
December 5, 2016

Math
P(1st=0) = 1/6 P(2nd=0) = 1/6 P(either) = 1/3
December 5, 2016

Math
The same as the probability that either of them is zero.
December 5, 2016

precalculus
(a) and (b) are equivalent, since you can write them as (y-k) = a(x-h)^2 (y-k) = 4p(x-h)^2 You have (b) and (c) right. I thought we already went over this...
December 5, 2016

Mathematics
No, you must check. You already have the alleged answers!
December 5, 2016

Maths
you are correct, but it seems a bit convoluted. Still, if it helps you sort out the quantities, good job.
December 5, 2016

precalculus
I don't see any questions. Just statements of the properties. If you understant (x-h)^2 = 4p(y-k) then I don't see what the problem is with (y-k)^2 = 4p(x-k) Go to wolframalpha.com and type in some functions and see what happens. For example, http://www.wolframalpha....
December 5, 2016

Calculus 1
x dx/dt + y dy/dt = 0 Now just plug in your numbers.
December 5, 2016

Math
the unit price per egg is 48/30. Add 15% profit and multiply by 100: (48/30)*1.15*100 = Rs 184
December 5, 2016

Calc
correct. Having trouble visualizing that, where h tries to change from concave down to up at x = -1, but fails, and stays concave down? h(x) = x^6/30 + 3x^5/20 + x^4/12 - x^3/2 - x^2 It's a strange bird. You can see it straightening out, then staying concave down until x=1...
December 5, 2016

Calc
As you can see, g'(1)=0 twice. So, g' is negative on both sides. That means the function is falling, comes to a momentary stop, and then keeps on falling. (Think of y=x^3, y'=3x^2. y'=0, but is rising on both sides.) g(1) is neither a max nor a min. Since g'...
December 5, 2016

Maths
a+4d = 3(a+d) a+11d = 2(a+5d)+1 Solve for a and d, then T16 = a+15d
December 5, 2016

algebra, mathematics
x + y = 33 y - 2x = 15
December 5, 2016

Silmultaneous Equations
I'll just use x and y, giving ?(5/8-(?5/8))x+cos(43°)y = 0 0.58778x + 0.73135y = 0 1/4(1+?5)x+sin(43°)y-2g=0 0.80902x + 0.68200y = 19.6 Now just solve by your favorite method (I suggest substitution).
December 5, 2016

Silmultaneous Equations
what do the LH and RH mean?
December 5, 2016

Math
no, it's not
December 5, 2016

math115
Your equation shows him just getting 1/2 time for extra hours. For time and a half, you need P(t) = 880 + 22*1.5(t-40) = 880 + 33(t-40)
December 5, 2016

Math
42
December 5, 2016

math
what, no possible ideas for this? Let x be the number. Then four times a number is 4x now work on the rest of the clues. Just put them into math symbols.
December 5, 2016

fundamental programming
x=5 while (x?0) read x
December 5, 2016

Math grade 10
the slope of AB is 1/4 So, you want a line with slope -4 that contains C(1,4). Use the point-slope form, and you have y-4 = -4(x-1)
December 5, 2016

Math - Coordinate Geometry
you have a slope (4) and an intercept (-3), so try the slope-intercept form: y = 4x-3
December 5, 2016

math
.25x + .60(90-x) = .53*90
December 4, 2016

Math
So, I guess you did not read the web page I suggested ... r = ed/(1+e sin?) r=4/(-2-6sin?) r = -2/(1+3sin?) so, e=3 and d=2/3 in x-y coordinates, that is (y-3/4)^2 - x^2/8 = 1/16 http://www.wolframalpha.com/input/?i=hyperbola+(y-3%2F4)%5E2+-+x%5E2%2F8+%3D+1%2F16 You can see ...
December 4, 2016

Algebra
one way is just plain substitution. You know that y = 5x-3, so use that in the other equation: y = -3x+5 5x-3 = -3x+5 8x = 8 x = 1 Now, y = 5x-3 = 5-3 = 2 substituting for x will also work, but then you have fractions to work with, since x = (y+3)/5 or (5-y)/3
December 4, 2016

Algebra
The + on the left means it's a circle or ellipse. The differing coefficients for x^2 and y^2 means it's an ellipse. In standard form, that is just x^2/25 + y^2/9 = 1
December 4, 2016

Math
You say Suppose m?438° what does that mean? Hmm. Maybe you mean m?4 = 38° Not sure what the figure looks like, but corresponding angles are congruent. Check for adjacent angles or alternate/vertical angles. It's kind of hard to answer a question about a diagram ...
December 4, 2016

PreCalc
every 10s the amount drops by 1/2, so m(t) = 5 * 2^(-t/10)
December 4, 2016

PreCalc
clearly, n(t) = 1500*(12000/1500)^t = 1500*8^t = 1500 e^(2.07944t)
December 4, 2016

Math
suppose I said 8 = r/4 How would you do that? Multiply by the denominator, right? So, r = Td Now divide by T to get d all alone: d = r/T
December 4, 2016

Math
We are talking about 7*24+1 = 169 hours. So, the clock loses 84.5 minutes in that time. ...
December 4, 2016

Math
depends on the coins.
December 4, 2016

Math grade 10
Just verify that they intersect at (3,3)
December 4, 2016

Maths
sorry. that's ?x-2?
December 4, 2016

Maths
y = 0.50 for x <= 2 0.50 + 0.10(x-2) for x > 2 technically, it is a step function, so y = 0.50 + 0.10⌈x-1⌉ for x > 2
December 4, 2016

Math
Just plug in your numbers. (a) H = 27.5 + 2.24*20 (d) 68 = 24+2.32F (e) as femurs lengthen, men grow more slowly
December 4, 2016

Maths
If the number is ab, then a = 2b 10a+b - 18 = 10b+a
December 4, 2016

Maths
a+b+c = 1000 a = b+120 b = c+110 b+120 + b + c = 1000 c+110+120 + c+110 + c = 1000 3c+340 = 1000 3c = 660 ...
December 4, 2016

Calculus
If the man's shadow has length s, then using similar triangles, when the man is x meters from the building, s/15 = 1.69/(15-x) s = 25.35/(15-x) ds/dt = 25.25/(15-x)^2 dx/dt Now plug in your numbers
December 4, 2016

Calculus
x^2+y^2 = 225 x dx/dt + y dy/dt = 0 now just plug in your numbers and solve for dy/dt
December 4, 2016

math
naturally, that would be 0.40 * 20, right?
December 4, 2016

Pre-calculus
These take some practice, but you soon learn the tricks of thinking... #1 r^2 = 4r cos? r = 4cos? #2 (r^2)^2 = 6(r^2 cos^2? - r^2 sin^2?) r^2 = 6(cos^2? - sin^2?) r^2 = 6cos(2?)
December 4, 2016

Math geometry
42
December 4, 2016

Pre-Calculus
This article should make things clear. Your function can be massaged to read r = -2/(1+3sin?) http://colalg.math.csusb.edu/~devel/IT/main/m11_conic/src/s08_polar-conics.html
December 3, 2016

Math, Quadratic Functions
xy = 108 x+2y = 30 x + 2(108/x) = 30 x^2 - 30x + 216 = 0 (x-12)(x-18) = 0 The yard is 12x9
December 3, 2016

Calculus
if n is even, r = a cos(n?) is a rosette with 2n leaves. Think about it. cos(n?) goes from 1 to 0 every time n? grows by pi/2. So, in [0,2pi], 6? goes in and out 12 times. You can always verify your work online, as at http://www.wolframalpha.com/input/?i=r%3D5cos(6%CE%B8)
December 3, 2016

algebra
The focus is (14,0) and the directrix is x=0 SO, you have a parabola opening to the right, with 2p=14, and vertex at (7,0) halfway from directrix to focus: y^2 = 28(x-7) http://www.wolframalpha.com/input/?i=parabola+y%5E2+%3D+28(x-7)
December 3, 2016

precalculus
your values for a,b,c are correct. However, your final answer is wrong, as you could have verified had you tried to check your answer. y = -1/2 x^2 + x + 6
December 3, 2016

maths(trigonometry)
You cannot mean 10A = 4/3 When you figure out what you mean, then just draw your triangle, and recall that sin? = y/r cos? = x/r
December 3, 2016

tss
the diameter is twice the radius: 10
December 3, 2016

Math
v = ?/4 * 0.5^2 * 100 = 25/4 ? ft^3
December 3, 2016

Math 10
20C3
December 3, 2016

History
Which is an impact of World War 1 A: German and Russian monarchies became stronger. B: The united states became the largest creditor nation. C: Europeans used their money to buy American goods. D: France no longer had a demand for British goods. My answer is B
December 3, 2016

Math
A prime number is a number whose factors are only 1 and itself like 17 is a prime number because it's only factors are 1 and 17. 25 is a composite number because it has other factors besides 1 and itself, 25. The factors of 25 are 1,5,and 25. That's why it's a ...
December 3, 2016

Math
well, 16/60 = 26.67% so, what % scored less?
December 3, 2016

intermediate algebra
well, it will double three times, right? So, that's 8 times the original amount...
December 3, 2016

Math
A man left 3/7 of his money to his wife, 1/2 of the remainder to his brother, and the rest he divided equally among his three children. If each of his children received $400, how much did his wife receive? starting with x, 3/7 went to wife, leaving 4/7 1/2 of that, 2/7, went ...
December 3, 2016

math
he spent the remainder of the 5 hours. That is, 5 - 2 3/10 = 2 7/10
December 3, 2016

Algebra
posting it again won't get it any more attention, especially after just 11 minutes! Just wastes your time and ours.
December 2, 2016

Algebra
8 - 3/4 c = 5 -3/4 c = -3 c = -3 * -4/3 = 4 check: 3/4 * 4 = 3 8-3 = 5
December 2, 2016

Math
well, these two angles add up to 90 degrees, right? So solve for x, and you can get the angle measures.
December 2, 2016

Math - Calculus @My bad.
Never mind. I rotated around the line y = -1.
December 2, 2016

Math - Calculus
The graphs intersect at (-4/3,32/3) and (1,6) We are only interested in x>0, so the volume is using discs v = ?[0,1] ?(R^2-r^2) dx where R=8-2x and r=6x^2 v = ?[0,1] ?((8-2x+1)^2-(6x^2+1)^2) dx = 782?/15 Since we are rotating around the line x = -1, the radius is increased ...
December 2, 2016

Math
using discs (washers), v = ?[0,3^(1/5)] ?(R^2-r^2) dx where R=3 and r=y=x^5 v = ?[0,3^(1/5)] ?(9-x^10) dx = 90?/11 3^(1/5) using shells, v = ?[0,3)] 2?rh dy where r=y and h=x=y^(1/5) v = ?[0,3)] 2?y^(6/5) dy = 90?/11 3^(1/5) You might have showed your work, right?
December 2, 2016

Pre-Calculus
tan?/sec? = tan?*cos? = sin? rsin? = 2 y = 2
December 2, 2016

Calculus
tan? = 4 ? = arctan(4) (C)
December 2, 2016

Calculus
plug and chug: 2xy = 3 2 rcos? rsin? = 3 so, (C)
December 2, 2016

Pre-Calculus
r = 4sec? r = 4/cos? rcos? = 4 x = 4
December 2, 2016

Pre-Calculus
recall that tan? = y/x so, your equation is just y/x = -?3 y = -?3 x
December 2, 2016

Calculus
your turn to show some work
December 2, 2016

Calculus
Since the region is rotated around x = -3, you should have ?((3+?(9-y^2))^2-9)
December 2, 2016

Calculus - Integrals
The curves intersect at (0,0) and (2?2,2?4) using discs, v = ?[0,2?2] ?(R^2-r^2) dx where R=?(4x) and r=x^2/2 v = ?[0,2?2] ?(4x-x^4/4) dx = 24??4/5 using shells, v = ?[0,2?4] 2?rh dy where r=y h=(y^2/4)-?(2y) v = ?[0,2?4] 2?y(?(2y)-(y^2/4)) dy = 24??4/5
December 2, 2016

algebra
actually, it's h(t) = 200 - 16t^2 so, use 11 for t and evaluate it.
December 2, 2016

Calculus
let f(x) = 4sinx, g(x) = 2cosx. the graphs cross at u=arctan(1/2), so the area is ?[0,u] (g-f) dx + ?[u,.7?] (f-g) dx
December 2, 2016

math
Since x>7, you want any number greater than 7. How hard is that? Only one choice fits.
December 2, 2016

Calculus
what's the trouble? The height of each small rectangle is just the distance between the curves, so a = ?[0,1] (2x^2-x^4) - (x^8) dx
December 2, 2016

algebra
look at the values for n n #people 0 4 1 4*3 2 (4*3)*3 = 4*3^2 ... n 4*3^n why do you repeat all the math? It's very distracting and annoying.
December 2, 2016

Maths
x-6 = (50-x)+12
December 2, 2016

Math
ab/2 = 12 a+b = 16
December 2, 2016

Math
already did! http://www.jiskha.com/display.cgi?id=1480652609
December 2, 2016

math
so, how many turns required for 1000m? 1000m * 1turn/2.2137m = ? turn
December 2, 2016

Algebra 1B
But it is not. Try again. It is A.
December 2, 2016

Algebra 1B
just solve for x when y=0. be careful, as A and D are almost the same
December 2, 2016

math
Drop an altitude from B to D on AC. Then triangles ABD and CBD are 30-60-90 right triangles. AD = DC = 3?3 so, AC = 6?3 a+b = 9
December 2, 2016

Math
well, the room is 4x3 tiles
December 2, 2016

Math
All are ok except #7 ?? and your answer formatting still sucks.
December 2, 2016

Check them please MAth
I don't see any of your answers to check. And your text formatting is totally bogus, D00d!
December 2, 2016

maths
Well 100% = 5/5 so, how many fifths are left?
December 2, 2016

Math
R*I = I ? is irrational I+I = I (usually) R^3 = R so ok there
December 2, 2016

Algebra
do you know the golden ratio?
December 2, 2016

algebra 2a solving systems using matrices
Nope. The matrix has no x in row 1.
December 2, 2016

Math
cos(180-x) = -cos(x) cos(90-x) = sin(x) so you have (0.5)cos^2(x)sin^2(x) = 0.05 cos^2(x) sin^2(x) = 1/10 sin^2(2x) = 1/40 sin(2x) = ±1/(2?10) ...
December 1, 2016

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