Wednesday

January 18, 2017
Total # Posts: 47,946

**Math**

see the related questions below. They should help you set up and solve your differential equation. If you get stuck, come back with what you have done so far.

*December 5, 2016*

**Calculus**

you are correct: http://www.wolframalpha.com/input/?i=plot+y%3Dx%5E3%2B1%2F4,+y%3D3x%2F4,+-1%3C%3Dx%3C%3D1

*December 5, 2016*

**Math**

x^3+2y^3 = 5xy 3x^2 + 6y^2 y' = 5y + 5xy' y'(6y^2-5x) = 5y-3x^2 y' = (5y-3x^2)/(6y^2-5x) y" = [(5y'-6x)(6y^2-5x)-(5y-3x^2)(12yy'-5)]/(6y^2-5x)^2 2xy(54x^3-270xy+108y^3+125) -------------------------------------- ...

*December 5, 2016*

**parametrics**

Your parametric equations are right. The second quadrant is pi/2 <= t <= pi

*December 5, 2016*

**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**

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*