Thursday

December 8, 2016
Total # Posts: 46,981

**Math**

F·dr = sinx dx + cosy dy + xz dz Now just crank it out, using the definitions of x,y,z: ?4t^3 sin(t^4) - 3t^2 cos(t^3) + (t^4)(t) dt = -cos(t^4) - sin(t^3) + 1/6 t^6 [0,1] = -1 + 1/6 = -5/6

*November 2, 2016*

**Math**

this is just like the others. W = ?F•dr see the other posts.

*November 2, 2016*

**Geometry (Please check my work)**

Nope. Reflecting across the line y = -5 means that the image is as far below the line as (-2,-1) is above it: 4 units. So, (-2,-1) -> (-2,-9) Same with the line x=1. 3 to the left, so 3 to the right. (-2,-9) -> (4,-9) Reflecting across the line y=k: (x,y) -> (x,k-(y-k...

*November 2, 2016*

**math**

a number divided by 3

*November 2, 2016*

**Algebra 2**

none

*November 2, 2016*

**Math**

500,000 * 1.04^3

*November 2, 2016*

**Maths**

If the number of sides is n, then we have 180(n-2)/n = 10(360/n)-84 n=15 So, the sum of its interior angles is 180(15-2) = 2340°

*November 2, 2016*

**@Writeacher**

Writeacher, you're all right! =)

*November 2, 2016*

**math**

well, did you look at the formula? If a line with slope m passes through (h,k), its equation is y-k = m(x-h) So plug in your numbers.

*November 2, 2016*

**Maths**

Those numbers make no sense, either as absolute quantities or as percentages.

*November 2, 2016*

**Algebra**

The others are 180-(5x-20) = 200-5x or 180-(70-4x) = 110+4x In either case, opposite angles are equal, so if you want the actual numeric measure, just set the two expressions equal, solve for x, and the evaluate the expressions.

*November 2, 2016*

**Math**

v(t) = 6t^2 + ? a(t) = 12t + ? The ? is because you did not specify the power of t for the "45" term Anyway, fill it out and use your numbers. scrub...

*November 2, 2016*

**Math**

so, why don't you show us what you did? If you meant n/-3 + 5 >= 4 just work it as usual: subtract 5 n/-3 >= -1 Now multiply by -3 and change direction n <= 3 The reason you change direction is just a shortcut for moving things around by addition and subtraction: ...

*November 2, 2016*

**Mathematics**

the slope is -2, so y-5 = -2(x-1) y = -2x+7 2x+y = 7 2x+y-7 = 0 x/(7/2) + y/7 = 1 take your pick

*November 2, 2016*

**piedad elementary school**

try dividing out the common factor: 100/300 = 1*100/3*100 = 1/3 * 100/100 = 1/3 and so on. You will find one of the fractions has no common factor to use.

*November 2, 2016*

**maa central**

#blue / #total = 5/10

*November 2, 2016*

**Calc III**

Using symmetry, you can just take 4 times the volume in the 1st octant: 4?[0,?/2]?[0,4cos?]?[0,?(16-r^2)] r dz dr d? = 4?[0,?/2]?[0,4cos?] r?(16-r^2) dr d? = -4/3?[0,?/2] (16-r^2)^(3/2) d? [0,4cos?] = -4/3?[0,?/2] (64sin^3?)-(64) d? = -256/3?[0,?/2] sin^3?-1 d? = 256/3 ?[0,?/2...

*November 2, 2016*

**Math**

I assume you want to simplify in some manner. 7(4log2-(log3+log5)) + 5(2log5-(3log2+log3)) + 3(4log3-(4log2+log5)) now combine like logs, and you wind up with log2 Or, you can combine the factors first: 7log16/15+5log25/24+3log81/80 log ((2^4/(3*5))^7 * (5^2/(2^3*3))^5 * (3^4...

*November 2, 2016*

**math**

recall the multipliers of Pascal's Triangle: 1 3 3 1 Now use those in the expansion.

*November 2, 2016*

**Ad.func**

Let x = the distance from the wall a = angle of elevation of the bottom of the picture b = angle subtended by the picture Then we have 1/x = tan(a) 4/x = tan(a+b) we want b = pi/6. So, (tana + tanb)/(1-tana*tanb) = 4/x Now just plug in 1/x for tan(a) and solve for x

*November 1, 2016*

**9th grade algebra (factoring with quadratic)**

#7: x^2 - 18x + 57 = 0 Looks like the quadratic formula is what you'll need: x = 9±?24 Or, you could complete the square, as was done in the following problems: x^2 - 18x + 57 = 0 x^2 - 18x + 81 = 24 (x-9)^2 = ±?24 x = 9±?24 The rest look good, except ...

*November 1, 2016*

**Trigonometry**

amplitude is (95-80)=15 center line is 80, so start with the assumption that the minimum occurs at midnight (0 hours): y = -15cos(kx)+80 The function has a period of 24 hours, so 2?/k = 24, making k=?/12 y = -15cos(?/12 x) + 80 Now we know that the max occurs at x=15, not x=12...

*November 1, 2016*

**Math**

First, be sure that f(0)=f(1). It does since f'(x) = 3x^2-4x+1 = (3x-1)(x-1) just find a value in the interval [0,1] where f'(x) = 0. Now it's just algebra. The calculus is done.

*November 1, 2016*

**Math**

It appears that g(x) is constant, so it does not matter what f is. Fix the typo. Then just substitute f(x) for x in the definition of g. (g?f)(x) = g(f(x)) That is, if g(x) = x+3, (g?f)(x) = g(f) = f+3 = 4x-5+3 = 4x-2

*November 1, 2016*

**maths**

well, there are 42 eggs in total. Now work out the rest, based on that.

*November 1, 2016*

**algebra**

the total round-trip distance is 2 * 4 2/3 = 9 1/3 so, ...

*November 1, 2016*

**Business math**

He gets 2 years of interest on the original 500, and 1 year on the extra x. So, we want 500(1 + .085/2)^(2*2) + x(1 + .085/2)^(2*1) = 1000

*November 1, 2016*

**maths**

clearly David had 75 oranges. The rest then can be easily found.

*November 1, 2016*

**Math**

If the larger radius is r, then we have ?r^2 = ?(r-3)^2 + 15? r^2 = r^2-6r+9 + 15 6r = 24 r = 4 check: 16? = ? + 15?

*November 1, 2016*

**Math**

no digit can be 10.

*November 1, 2016*

**Chem**

It's hard to understand why you ask such a general-knowledge question here, rather than just going first to google. This would be a good place to start, both for the information, and the explanations on why the above question is rather ill-formed. https://www.webelements....

*November 1, 2016*

**English**

while syntactically gerunds are equivalent to infinitives in these uses, in practice, I doubt you will find anyone using the constructions in 2 and 4. I have heard #6. I guess because the word preceding the gerund is an adjective rather than a noun. #7 and 8 are both common, ...

*November 1, 2016*

**Science**

the acceleration indicates how much the velocity changes each second. Hence, v = at (m/s) = (m/s^2)(s)

*November 1, 2016*

**Math**

26 * 5 = 130

*November 1, 2016*

**Math**

12 + 14 = 26 * 5 This method is way easier

*November 1, 2016*

**hellllllpppp**

23/63 = 36% So

*November 1, 2016*

**hellllllpppp**

Damon is an uneducated tutor

*November 1, 2016*

**hellllllpppp**

He is un educated

*November 1, 2016*

**math**

LCM(84,35,52) = 5460

*November 1, 2016*

**MATH**

14f + 6e - 51

*November 1, 2016*

**MATH**

14f - 30 - 15e

*November 1, 2016*

**Physics**

acceleration= changevelocity/time

*November 1, 2016*

**Math**

If I understand this correctly, then if the digits of m are a and b, we have m = 10a+b and so 100a+10n+b = 11(10a+b) 100n+10a+b = 21n But this comes out with negative solutions. Maybe you can fix my logic and take it where it's supposed to go.

*November 1, 2016*

**Maths**

to find an average, add up all the values and divide by how many there are. Do those values end in 1 (one) or l (el)?

*November 1, 2016*

**Maths**

1cm = 10mm, so 54mm = 5.4 cm. 1/10=5.4/x, where x is equal to 54 (10 x 5.4).

*November 1, 2016*

**Pre-algebra**

It's -18/1

*November 1, 2016*

**PLEASE CHECK OPERATIONS WITH FRACTIONS**

1. A 2. A 3. C 4. A 5. B 6. B 7. D 8. B 9. A

*November 1, 2016*

**PLEASE CHECK OPERATIONS WITH FRACTIONS**

6. B - Correct 7. C - Incorrect it actually = D, -1/8 8. C - Incorrect it actually = B, 21 8/9 9. B - Incorrect it actually = A, -15/28

*November 1, 2016*

**PLEASE CHECK OPERATIONS WITH FRACTIONS**

So basically it is 1. A 2. A 3. C 4. A 5. B

*November 1, 2016*

**PLEASE CHECK OPERATIONS WITH FRACTIONS**

1. A - Correct 2. A - Correct 3. D - Incorrect, It = 1 71/72 So it would = C - 2 4. A - Correct 5. C - Incorrect, It = 34 122/221 So it would = B - 35

*November 1, 2016*

**PLEASE CHECK OPERATIONS WITH FRACTIONS**

Ok

*November 1, 2016*

**Maths (really hard)**

see related questions below

*November 1, 2016*

**Mathematics**

the equation is based on the fact that the range of water's freezing point to its boiling point is 180°F and 100°C So, the F degrees are 5/9 as big as the C degrees. So, it takes more of them to cover the range. Moreover, the F scale sets water's freezing point...

*November 1, 2016*

**Maths**

C = (5,-5/2) AC^2 = (5-4)^2 + (-5/2+3)^2 = 1 + 1/4 = 5/4 CB^2 = (6-5)^2 + (-2+5/2)^2 = 1 + 1/4 = 5/4

*November 1, 2016*

**math**

well, they all three add to 180, so ...

*November 1, 2016*

**Algebra**

If I understand this correctly, then if the digits of m are a and b, we have m = 10a+b and so 100a+10n+b = 11(10a+b) 100n+10a+b = 21n But this comes out with negative solutions. Maybe you can fix my logic and take it where it's supposed to go.

*November 1, 2016*

**help maths**

just google the topic. You might start here: https://www.whitman.edu/mathematics/calculus_online/section09.06.html I'm sure your text has examples of finding the centroid. If you are unsure about the shape, just see http://www.wolframalpha.com/input/?i=y%5E2+%3D+x(1-x)%5E2

*November 1, 2016*

**help maths**

PI, not pie!!! The center of gravity is clearly on the x-axis, so we just need to find the x-coordinate. Recall that x-bar = (integral x*f(x) dx)/(integral f(x) dx)

*November 1, 2016*

**Converse of the Pythagorean Theorem**

it's a right triangle if the longest side qualifies as an hypotenuse: a^2+b^2=c^2 Since 7^2 < 5^2+6^2 the triangle is acute. Similarly, if the c^2 > a^2+b^2, the triangle is obtuse.

*November 1, 2016*

**Calculus**

rearranging things a bit, we have y^3 = 9x^2+x-5 3y^2 y' = 18x+1 y' = (18x+1)/(3y^2) at (-3,1) that means y' = -53/3 However, (-3,1) is not on the curve. Typo??

*November 1, 2016*

**Trig**

2sinx = 1 - 2cosx sinx+cosx = 1/2 Now, sin(x+Ï€/4) = sinx cosÏ€/4 + cosx sinÏ€/4 = 1/âˆš2 (sinx+cosx) SO, what you have is just âˆš2 sin(x+Ï€/4) = 1/2 sin(x+Ï€/4) = 1/âˆš8 x+Ï...

*November 1, 2016*

**Sats**

depends entirely on the distribution.

*November 1, 2016*

**pre-calc**

5000*1.1^20 vs 5000*(e^.1)^20

*November 1, 2016*

**pre calculus**

if the side is x, then the other side is 4000/x. So, we have x^2 + (4000/x)^2 = (x+10)^2 x â‰ˆ 91 check: the rectangle is about 91x44 The diagonal is 101 = 91+10

*November 1, 2016*

**7TH GRADE mATH**

1500 * .0425 * 4

*November 1, 2016*

**calculus**

Hmmm. I see that my characters for pi and sqrt have been mangled. They appeared correctly as I typed them, but on redisplay are junk. r = sqrt(5/pi), h=2

*November 1, 2016*

**calculus**

v = Ï€r^2 h = 10 so, h = 10/(Ï€r^2) The surface area is a = 2Ï€r(r+h) = 2Ï€r(r + 10/(Ï€r^2)) = 2Ï€r^2 + 20/r da/dr = 4Ï€ - 20/r^2 = (4Ï€r^2-20)/r^2 da/dr=0 when 4Ï€r^2=20, or r=â&#...

*November 1, 2016*

**geometry**

if you mean that the center is (4,-1) and (8,2) lies on the circle, then r^2 = (8-4)^2+(2+1)^2 = 25 so the circle is (x-4)^2 + (y+1)^2 = 25

*October 31, 2016*

**brief calc**

a = âˆ«[4,5] 6x dx = 27 or, since the area is just a trapezoid of height 1, a = (24+30)/2 = 27

*October 31, 2016*

**Algebra**

the angles add to 180, so since R=Q+20, Q=R-20 S=Q+115 = (R-20)+115 = R+95 Q+R+S=180 R-20 + R + R+95 = 180 ...

*October 31, 2016*

**Algebra2**

Given no choices, I'd just have to say those closest to the turning points...

*October 31, 2016*

**Algebra2**

Which points are the best approximation of the relative maximum and minimum of the function? f(x)=x^3+3x^2-9x-8

*October 31, 2016*

**Algebra**

2(x + 4x-33) = 104

*October 31, 2016*

**Algebra**

add 9, multiply by 5, divide by -2 and change direction

*October 31, 2016*

**Algebra**

well, just plug and chug: R(x+h)-R(x) ---------------- h

*October 31, 2016*

**Algebra2**

A quadratic equation can be written in vertex form or in standard form. Sometimes one form is more beneficial than the other. Identify which form would be more helpful if you needed to do each task listed below and explain why. a- factor the equation b- graph the parabola c-...

*October 31, 2016*

**Algebra2**

y = -x^2+12x-4 = -(x^2-12x)-4 = -(x^2-12x+36)-4+36 = -(x-6)^2 + 32

*October 31, 2016*

**Algebra2**

What is the vertex form of the equation? Show steps y=-x^2+12x-4

*October 31, 2016*

**Algebra2**

thank you

*October 31, 2016*

**Algebra2**

Complex numbers can be graphed on the xy coordinate plane. TRUE OR FALSE My answer is yes

*October 31, 2016*

**Algebra**

still can't figure out what you mean by pedro works in 3 days and juan in 4 days does that mean that Pedro works for 3 days, and then Juan works for 4 days? It appears that you are saying it takes Pedro 3 days, and it takes Juan 4 days. Then you ask how long it takes each ...

*October 31, 2016*

**plz sir reiny sir steve sir damon help sor bob**

just use the chain rule d/dx arccosh(u) = 1/√(u^2-1) du/dx so, if u = x/√3, that becomes 1/√(x^2/3 - 1) * 1/√3 = 1 / √(x^2-3) since you know that cosh^2(u) = 1+sinh^2(u) d/dx coshu = sinhu, you have y = arccosh(u) coshy = u sinhy y' = 1 y'...

*October 31, 2016*

**math**

600 * 1.04^6

*October 31, 2016*

**maths**

the slope of AB is -1/4 So, the slope of AC is 4 AB has length √68 = 2√17 So, AC has length √17 = √(1^2+4^2) That means that C = A+(1,4) = (2,9)

*October 31, 2016*

**pre algebra PLZZZ help**

what string? and certainly, estimation is often easier than detailed calculation.

*October 31, 2016*

**Pre-Calc/ Trig**

4cos^2(2θ-π) = 3 cos^2(2θ-π) = 3/4 since cos(a-b) = cosa cosb + sina sinb, cos(2θ-π) = -cos(2θ) cos^2(2θ) = 3/4 cos(2θ) = ±√3/2 now cos π/6 = √3/2 so, 2θ = π/6, 5π/6, 7π/6, 11π/6 &#...

*October 31, 2016*

**math**

facing east, of course.

*October 30, 2016*

**MS.SUE PLEASE HELP!!!**

(3/4)(z+8) 6(3x+y) -5(2a+5) in each case, just divide each term by the number you want to factor out.

*October 30, 2016*

**Permutations**

11*10*9 = 990 or 11!/(11-3)! = 11!/8!

*October 30, 2016*

**Algebra II**

just split up the real and imaginary parts, as usual! 19+42i-21yi+28y = (19+28y) + (42-21y)i

*October 30, 2016*

**calculus**

∫√(v^2 sin^2(2π/T t)) dt Looks to me like just ∫|v sin(2π/T t)| dt The absolute value throws in a wrinkle, but the integral is simple enough.

*October 30, 2016*

**Calculus differentiable and continous identify**

For continuous, ya got me. Only F looks like it fails. For differentiable, surely F fails, because it isn't even continuous. Also, (a),(b),(d) fail because of the cusps. I am assuming that d(0) is defined somewhere on the y-axis. (f) fails because the ends of the semi-...

*October 30, 2016*

**Physics 11 steve or any physics teacher helpURGENT**

The total momentum must be conserved. If the boy slides away to the left, the box must move to the right, since momentum is a vector quantity.

*October 30, 2016*

**algebra 2**

If x is the number of years, you need (1 + .038/2)^(2x) = 3000/2000

*October 30, 2016*

**algebra**

80 is 4 half-lives, so at t=0, it was 16 (2^4) times as great.

*October 30, 2016*

**Algebra**

after x years, the value is 14000 * 0.98^x

*October 30, 2016*

**Calculus AB**

#1 f' = (3x+2)e^x since e^x is always positive, just determine where 3x+2 is positive, etc. #2 remember the point-slope form of a line. a) y= x^2 + (e^x)/(x^2 +1) at the point x=3. y' = 2x + (x-1)^2/(x+1)^2 e^x y(3) = 9+e^3/10 y'(3) = 6+e^3/4 So, you want the line ...

*October 30, 2016*

**Math**

type in your functions here, and see whether you can see how to arrive at the solutions. http://www.wolframalpha.com/input/?i=%7C(x-3)%2F2%7C

*October 30, 2016*

**math**

not sure what you have against a simple minus sign, dividion symbols, etc. The rest of us just use simple ascii characters, such as + - / * < <= > >= all are correct except #8 c+6 < -20 c < -26

*October 30, 2016*

**Pre-Calculus**

there are a few standard angles whose exact values we know. By combining them we can get exact values for other angles.

*October 30, 2016*