Friday

October 28, 2016
Total # Posts: 45,430

**mathematics**

LCM(24,30,36) = 360

*October 10, 2016*

**Geometric progression**

ar^4 = 81 ar = 24 r^3 = 81/24 = 27/8 r = 3/2 Now find a.

*October 10, 2016*

**Algebra**

separate it into 2+5+8+... and 3+6+9+... add the two sequences together. Each is easy to figure, right? Or, make it a single sequence 6n-1 ... 5+11+17+...

*October 10, 2016*

**calculus**

√(4x+y)+√(3xy) is not a curve. It is a surface. I guess you meant √(4x+y)+√(3xy) = 10 Hmmm. Maybe not, since that does not lead to the value you give. Try again with the post, and maybe show some intermediate steps.

*October 10, 2016*

**Math**

ar^7 = 348 ar^4 = 48 divide: r^3 = 29/4 now you can find a.

*October 10, 2016*

**Calculus**

dy/dt = cosz dx/dt = -2sinz dy/dx = -1/2 cotz d^2y/dx^2 = [d/dt(dy/dx)]/(dx/dt) = -1/2 csc^2(z) / -2sinz = -1/4 csc^3(z) too bad you didn't show any of your work...

*October 10, 2016*

**calculus**

sin(xy)+x^5+y^5=c cos(xy)(y+xy') + 5x^4 + 5y^4 y' = 0 y*cos(xy) + x*cos(xy)y' + 5x^4 + 5y^4 y' = 0 (x*cos(xy) + 5y^4)y' = -(y*cos(xy) + 5x^4) y' = y*cos(xy) + 5x^4 - ------------------------- x*cos(xy) + 5y^4

*October 10, 2016*

**Math**

x^2-3x+2 = (x-1)(x-2)

*October 10, 2016*

**Calculus**

depends. Is the region a 2x2 grid, or a 1x4 grid? In the first case, it will be 600x600. In the 2nd case, it will be 900x360.

*October 10, 2016*

**MATH**

no way to tell

*October 10, 2016*

**maths**

Figure the price per lemon divide the selling price by the cost (15/8) / (10/6) = 9/8 = 1.125 or a 12.5% profit

*October 10, 2016*

**MATH**

fix the typo

*October 10, 2016*

**Algebra**

they made 54 candles in 2 hours. Use that rate.

*October 10, 2016*

**Maths**

here's what I get, as you have written it. http://www.wolframalpha.com/input/?i=2%C3%B7%E2%88%9A5%2B%E2%88%9A3%2B1%C3%B7%E2%88%9A3%2B2-3%C3%B7%E2%88%9A5%2B%E2%88%9A2 I suggest some parentheses if you had intended other groupings

*October 9, 2016*

**Math**

just divide by the earth weight.

*October 9, 2016*

**physics**

If A has 10 times the mass, Fa/Fb = 10 If A is 10 times as far, Fa/Fb = 1/100 Now combine the two.

*October 9, 2016*

**math**

1/x - 1/(x-2) = -2/15

*October 9, 2016*

**math**

The reciprocal of a number minus the reciprocal of two less than the number is -2/15. find the number.

*October 9, 2016*

**Maths**

8 times as much as he saves.

*October 9, 2016*

**pre cal**

the fraction remaining after t hours is .64^(t/9) now plug in your numbers

*October 9, 2016*

**Math**

.50x + .20(45-x) = .30(45)

*October 9, 2016*

**math**

x+y=40 3.6x+4.6y = 156 now crank it out.

*October 9, 2016*

**precalculus**

oops - forget the sin example. Booooguss! I was thinking arcsin. 1/sin(4π11)

*October 9, 2016*

**precalculus**

sin(1/4π11) whatever that means or sec(π/2-4π11) co- means complementary angle.

*October 9, 2016*

**Math**

Set the partial derivatives to zero for extrema. Both must be zero.

*October 9, 2016*

**Math**

since distance = time * speed, 3(x + x-4) = 400-40

*October 9, 2016*

**precalculus**

see related questions below again

*October 9, 2016*

**Math**

(3/4 - 1/5) pi

*October 9, 2016*

**Math**

21 49/10 ...

*October 9, 2016*

**math**

the "direction change" rule is just a shortcut for when things move from one side of the inequality to the other. When adding and subtracting, or multiplying/dividing by a positive value, the direction never changes. -4x < 8 divide by -4 and change direction: x &...

*October 9, 2016*

**value**

max height reached at 2 seconds. use that.

*October 9, 2016*

**MATH**

7.50 * 3

*October 9, 2016*

**Variation**

D = kT^2 when T=13, D = 169k when D=648, T = √(648/k) Supply the missing info, and you can get numbers.

*October 9, 2016*

**maths(cbse)**

Draw a diagram. The half-chords are legs of right triangles, with the radius as hypotenuse. The two triangles require that r^2 = 4^2 + 3.5^2 r^2 = 8^2 + 5^2 Clearly the two values do not agree, so the assertion is false.

*October 9, 2016*

**Calculus, Related Rates**

Why are you looking for speeds? The question is about distance. Let's assume that the miles are nautical miles, so no conversions are necessary. At time t hours, the distance z is found using z^2 = (60-15t)^2 + (36-10t)^2 = 325t^2 - 2520t + 4896 2z dz/dt = 650t - 2520 The ...

*October 9, 2016*

**MATH**

If John ate half of what Peter ate, clearly Peter ate more. so, what is 1/2 of 2/8? what is 1/2 of 2?

*October 9, 2016*

**math**

see related questions below. always a good idea before posting the same problem again!

*October 9, 2016*

**Algebra 1**

13+ w/7 = -18 subtract 13: w/7 = -31 multiply by 7: w = -217

*October 9, 2016*

**math**

total cost: 270*3 = 810 total eggs: 30*3 = 90 eggs sold: 90-9 = 81 at a price p, she made 20%, so 81p = 810 * 1.20

*October 9, 2016*

**precalculus help**

The asymptotes intersect at the center: (1,2) The foci are at x=1, so the axis is vertical, giving (y-2)^2/a^2 - (x-1)^2/b^2 = 1 If a focus is at (1,12), c=10 c^2 = a^2+b^2 The slope of the asymptotes is a/b = 1/3, so b=3a c^2 = a^2+b^2 = 100, so a^2=10, b^2=90 (y-2)^2/10 - (x...

*October 9, 2016*

**Math**

x = number of $5 discounts ticket price: 30-5x attendance: 40000 + 10000x revenue: (40000 + 10000x)(5+(30-5x)) max revenue at x=7 Huh? Pay people $5 to attend? Check for typos.

*October 8, 2016*

**math**

1 man can paint (75/5)/20 = 3/4 house/day work with that.

*October 8, 2016*

**Math**

37000*1.085^n = 93000

*October 8, 2016*

**Trig**

You just need to review your formulas: http://www.sosmath.com/trig/prodform/prodform.html and recall that for trig functions, 345° is the same as -15°

*October 8, 2016*

**maths**

1000pc/2hr * 24hr/day * 1box/50pc * $3/box * x days = $9000 Now just solve for x

*October 8, 2016*

**maths**

well, they currently have 60 computers, so ...

*October 8, 2016*

**geometry**

you just need to find r. You have a point on the circle, which is r units away from the center. Thus, (3-8)^2 + (7-2)^2 = r^2 now you can easily find the area.

*October 8, 2016*

**maths**

We want their rate of painting in ft^2/hr. Thus b = 2d d + b = 2400/4 d + b + s = 3600/3 Solve for s, and then find s * 4.45

*October 8, 2016*

**Statistics and**

144-(31+91-14)

*October 8, 2016*

**Set Theory**

34-22

*October 8, 2016*

**Math**

no. see the "thousandths"? There will be a decimal point. one thousandth is 1/1000 or .001

*October 8, 2016*

**Loan**

Just make the usual Venn diagram. The number is 60+23-68 = 15

*October 8, 2016*

**physics**

1/5.4^2 * g

*October 8, 2016*

**College Algebra**

1/x = 1/8 + 1/6

*October 8, 2016*

**algebra**

just multiply the two numbers. But it will not be accurate. It is likely that Idahoans eat more potatoes than the average American.

*October 8, 2016*

**Math**

If the base has dimensions x and y, and the height is z, you want to minimize 5xy + 4*2z(x+y) subject to xyz = 135 Now use your favorite linear programming technique. See whether you can arrive at the solution of 540 at (6,6,15/4) These things usually work out so that two of ...

*October 8, 2016*

**physics**

how long does it take to stop, with acceleration a? 22.5t + 1/2 at^2 = 41 Now, with that t, 22.5 + at = 0 That gives you the value of a. F = ma

*October 8, 2016*

**Projectile Motion Help**

you can see how that formula was achieved if you read the article on trajectory in wikipedia. Maybe your textbook also explains how the formula was derived. In any case, just use it to get your answer!

*October 8, 2016*

**math**

(1/2 + 1/3)x = (1/4 - 1/5)x + 188

*October 8, 2016*

**math**

just solve for x in −0.0055x2 + 1.2x + 10 = 3

*October 8, 2016*

**value**

You want <x,y> such that <8,0>+<5cos30°,5sin30°>+<x,y> = <0,0> then you can get the direction of <x,y>

*October 8, 2016*

**math**

If the folded up edges have length x, then the base is 14-2x The area is thus a = ((14-2x + √2 x)+(14-2x))/2 * x/√2 da/dx = (1-2√2)x + 7√2 da/dx=0 when x = 4+√2 So, the base is 14-(4+√2) = 10-√2

*October 8, 2016*

**math**

After A, 5/8 remain. So, how much did B get?

*October 8, 2016*

**Math**

p = b+12 now write the other equation, and solve for p. hint: last year, their ages were p-1 and b-1

*October 8, 2016*

**physisc**

using g=10m/s^2, we have h - 4t - 5t^2 = 0 h - 20 - 125 = 0 h = 125 m

*October 8, 2016*

**maths**

the two acute angles are complementary. Or, the three angles sum to 180 (as in all triangles)

*October 8, 2016*

**math**

tan(π/4+x/2) = (tan π/4 + tan x/2) ------------------------- 1 - tan π/4 tan x/2 (1+tan(x/2))/(1-tan(x-2)) see where this takes you, and recall the half-angle formula for tan(x/2)

*October 8, 2016*

**maths**

-16t2 + 250t = 500 solve for t

*October 8, 2016*

**Math**

$10.50/hr * 8hr/day * 7day = $(10.50*8*7)

*October 8, 2016*

**Math**

sinh2x =8coshx 2sinhx coshx - 8coshx = 0 2coshx(sinhx-4) = 0 coshx=0 (no solutions) sinhx = 4 x = log(4+√17) http://www.wolframalpha.com/input/?i=sinh2x%3D8coshx

*October 7, 2016*

**Math**

I assume you mean (√3 x^3 + 3√3 y^3 + 5√5 - 3√30 xy Is that right, or did I misinterpret your somewhat murky syntax? And just what is it you want to do with the expression?

*October 7, 2016*

**Math**

lawn only: 45*30 lawn+path: (45+10)(30+10) area of path: (lawn+path)-(lawn only) ratio: duh

*October 7, 2016*

**Algebra**

#1: (-1)(4-c) (-1)(4)+(-1)(-c) -4+c No ideas at all on the others?

*October 7, 2016*

**Trig**

ditto - same song, different verse

*October 7, 2016*

**Trig**

draw your triangle tanA = 2/1 sinA = 2/√5 cosA = 1/√5 sin2A = 2sinAcosA = 4/5

*October 7, 2016*

**Math**

xy = 800 f = x+2y-4 To minimize p, substitute in for x or y, and find where p'=0. Check to be sure it does not matter where the gate is. (on the x side or the y side)

*October 7, 2016*

**MATH**

you might start here: http://www.mathsisfun.com/geometry/ellipse-perimeter.html

*October 7, 2016*

**Algebra**

If |y+4| < 1 then you want all the numbers that are less than 1 unit away from -4. -5 < y < -3

*October 7, 2016*

**Precalculus**

(a) let x=t, y=h(t) (b) as with all parabolas, the vertex is at -b/2a (c) vo is v sinθ now crank it out

*October 7, 2016*

**Physics (PLEASE HELP PRONTO)**

a = g sinθ

*October 7, 2016*

**Calculus**

Review your text section (probably Lagrange multipliers), and see whether you can come up with this solution: http://www.wolframalpha.com/input/?i=minimize+4y%5E2-29x%5E2+subject+to+3x%2By%3D21

*October 7, 2016*

**math**

oops. That figure applies if no girls graduate. If all the girls graduate, then 9/16 + 3/8 = 15/16 may graduate.

*October 7, 2016*

**math**

(9/10)(5/8) = 9/16

*October 7, 2016*

**algebra**

well, 1000m = 1km, so ...

*October 7, 2016*

**Geometry**

it's 3 ft on each side (left&right, top&bottom), so 12 becomes 18, 15 becomes 21. 2(18+21) = 78

*October 7, 2016*

**Math**

either place them all over a common denominator, and then sort the numerators, or convert all to decimal, and then it's easy to sort them.

*October 7, 2016*

**Math**

you want 5+1.00x = 8+0.75x

*October 7, 2016*

**Geometry**

so, which is it - y = -2, or x = -2?

*October 7, 2016*

**math**

use your product to sum formulas: 5 cos4x cos8x = 5/2 (cos12x + cos4x) those are easy, right?

*October 7, 2016*

**Mathematics of growth rate! Need help!**

A*1.05^70 = 3000000 now take logs and solve for logA or, A = 3000000/1.05^70 = (3000000^(1/70)/1.05)^70

*October 7, 2016*

**precalc**

you need to review your ellipses. See whether you can derive these properties: http://www.wolframalpha.com/input/?i=ellipse+x%5E2%2F4%2By%5E2%2F9%3D1 Your other ones should also be evident.

*October 7, 2016*

**math**

just plug in the values and check.

*October 7, 2016*

**Math - Calculus 1**

let f(x) = x^4 - x^2 df = (4x^3 - 2x) dx let x=1, dx=0.1 df ≈ (4-2)(0.1) = 0.2 f(x+dx) ≈ f + df = 0 + 0.2 real value: 0.2541

*October 7, 2016*

**Maths**

R = 14/10 W W = 10/14 R = .714 R so, it's 28.6% less

*October 7, 2016*

**Calculus - Related Rates**

draw a diagram. You can see that if the rocket is at height y, tanθ = y/100 so, sec^2θ dθ/dt = 1/200 dy/dt Now just plug in your numbers and find dy/dt

*October 7, 2016*

**math**

C(n) = C(P(h)) = .35P(h)+1000 = 0.35(375h)+1000

*October 7, 2016*

**maths**

well, you know that the solution to y' + 2y = 0 is y = c e^(-2x) Now just come up with the other part. Besides your class text, take a look at a similar problem here: https://au.answers.yahoo.com/question/index?qid=20100317130334AAtWVqs

*October 7, 2016*

**Physics urgent pleasw**

h(t) = 10.0 - 2.0t - 4.9t^2 now just find t when h=0

*October 7, 2016*

**Math**

as it stands, there are 100 marbles, with blue making up 14% So, for it to be 24%, you need 14/24 * 100 = 58.3 24% of 58 = 13.92 So, 14 marbles would be about 14% of 58

*October 6, 2016*