Saturday

October 22, 2016
Total # Posts: 45,160

**physics**

Since the force is inversely proportional to the square of the distance, it will be g * (R/(R+8600))^2 where R is the earth's radius.

*October 10, 2016*

**Math**

hard to mix commas with operators

*October 10, 2016*

**Math**

5/3xt1=2

*October 10, 2016*

**math**

tanA = 26.0/65.2 B = 90-A

*October 10, 2016*

**math**

x/67 = 71/100

*October 10, 2016*

**Math**

since time = distance/speed, if the boat's speed was s, then 70/(s-5) = 95/(s+5) s = 33 avg speed = totaldistance/totaltime = (70+95)/(70/28 + 90/38) = 1254/37 or 33.89 mi/hr

*October 10, 2016*

**Maths**

"sum" means "add" I assume your calculator can do that...

*October 10, 2016*

**Math help**

x = tanθ x^2+1 = sec^2θ dx = sec^2θ dθ and now your integrand becomes tan^3θ/secθ * sec^2θ dθ = tan^3θ secθ dθ = tan^2θ (secθ tanθ dθ) = (sec^2θ - 1) (secθ tanθ dθ) let u = secθ...

*October 10, 2016*

**physics**

Viy = 11 sin75° h = Viy t - 4.9t^2 solve for t in h=0, then Vy = Viy - 9.8t Use the t from above to get Vfy

*October 10, 2016*

**Quantitative Reasoning**

depends on the amount of ice, doncha think? Also, you need to know the surface area of the oceans. A large ocean will rise less than a small one for the same amount of ice. Also, a given volume of ice produces less volume when melted. There is so much missing in this question.

*October 10, 2016*

**Algebra**

x = number of $1 reductions price: 50-x demand: 600+20x R(x) = (50-x)(600+20x)

*October 10, 2016*

**Pre-Calculus**

check out the volume of a spherical cap: https://en.wikipedia.org/wiki/Spherical_cap

*October 10, 2016*

**maths**

get out your calculator or, just type that into the google search box -- it will calculate for you.

*October 10, 2016*

**pre-calc**

(ax^2 + bx + c)(x+2) + d = ax^3 + (2a+b)x^2 + (2b+c)x + (2c+d) so, a=3 2a+b = 0 2b+c = 2 2c+d = 1 now just crank it out.

*October 10, 2016*

**Maths**

429.07 * 100 = 42907

*October 10, 2016*

**college algebra**

You may want the height (h) or the length (L). h/20 = 0.3 L^2 = 20^2 + h^2

*October 10, 2016*

**Math**

Or, you can say that if |x| = 4 x = ±4 so, if |x-8|-15 = -6 |x-8| = 9 x-8 = ±9 ...

*October 10, 2016*

**Math**

Let's say there are m marbles. The clues given are: b+r+y = m r/m = 2/5 b/y = 5/7 r = 2m/5 y = 7b/5 so b+r+y = m b+(2m/5)+(7b/5) = m 12b/5 = 3m/5 b/m = (3/5)(5/12) = 1/4

*October 10, 2016*

**college algebra**

If the statue's height is h, then using similar triangles (from the diagram you drew, right?): h/c = a/b Now just plug in your numbers and solve for h

*October 10, 2016*

**Math**

If you followed those instructions, even without the typos, I'm sure you were confused! 3x + 9 = 7x - 11 subtract 3x: 9 = 4x-11 add 11: 20 = 4x divide by 4: 5 = x

*October 10, 2016*

**Math**

yes, 3 is one answer

*October 10, 2016*

**Math**

number between 600,000 and 700,000 6xx,xxx The digit in the hundreds place is 3. 6xx,3xx The digit in the ten thousands place is 1 more than the digits in the thousands and hundreds place. 643,3xx The sum of the digits in the ones and tens place equals the digits in the ...

*October 10, 2016*

**science**

1/R = 1/40 + 1/60

*October 10, 2016*

**Physics**

PV=kT since P is constant, V/T = k/P is constant. Thus, you want V such that V/273 = 50/293

*October 10, 2016*

**Physics**

think about it. the dropped coin reaches you with exactly the same velocity as you threw the sandwich.

*October 10, 2016*

**math**

9-7 = 9+(-7)

*October 10, 2016*

**math**

(10 2/3) / (3/4) = 32/3 * 4/3 = 128/9 = 14 2/9 So, there will be 14 plants fertilized, with some left over.

*October 10, 2016*

**physics (question impossible to solve)**

huh - I guess it's impossible to solve. Or, maybe you just need to review what static friction is.

*October 10, 2016*

**Physics**

v = vo + at now just plug in your numbers. The speed changes by 1.24 m/s every second.

*October 10, 2016*

**physics**

The triple product is just the determinant |ax ay az| |bx by bz| |cx cy cz|

*October 10, 2016*

**Calculus**

you want the tangent line to the curve at x=0. In a small neighborhood, the curve will stay close to the tangent line. (In fact, any curve is "straight" in a small enough interval!) So, you know that at x=0.3, the curve will be fairly close to the tangent line, which...

*October 10, 2016*

**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*