Monday

May 30, 2016
Total # Posts: 40,886

**maths**

what do you have against fractions? 3/8 + 1/4 = 3/8 + 2/8 = 5/8
*March 25, 2016*

**physics**

P = EI = 240*5 = 1200 = 1.2kW
*March 24, 2016*

**Geometry**

for the flagpole, draw a diagram. Draw a line parallel to the ground at the level of the top of the flagpole. The two angles mentioned are alternate interior angles, so they are congruent. the slope is the tangent of the angle. So, what angle x has tan(x) = 1/12 ? Take a look ...
*March 24, 2016*

**Algebra**

Just as with the baker, let x = acres of wheat y = acres of barley You want to maximize p=450x+350y subject to x+y >= 15 x+y <= 20 200x + 150y <= 2400
*March 24, 2016*

**Algebra**

If there are x packs of waffles and y packs of muffins, you want to maximize p = 1.50x+2.00y subject to 3/4 x + y <= 250 6x + 3y <= 1200
*March 24, 2016*

**geometry**

Or, using the formula area = 1/2 * apothem * perimeter, that will give you the perimeter. 1/5 of that will be the side length.
*March 24, 2016*

**geometry**

a regular pentagon has an apothem of 3.2 and an area of 37.2 cm. What is the length of one side of the pentagon?
*March 24, 2016*

**english help please!!**

google is your friend. I searched for marilyn cross pilot and got a bunch of hits on The Cold Equations, and discussions of the story and characters. I'd think you'd try google first before running here and expecting someone else to do your work for you. I know, I know...
*March 24, 2016*

**algebra**

I assume, but cannot be sure, that you meant f(x) = (x^4-4x^3)/(3-4x^2) + 1 since 3-4x^2+1 is kind of pointless. The denominator is zero when x = ±√3/2, so that is where the vertical asymptotes are. Before going any further, it'd be nice to know whether my f(x...
*March 24, 2016*

**Calculus Applied Integrals**

Just as a check, ∫[12.1,22.1] 1000 π (12.2^2)*9.8 x dx = 7.83595*10^8 which agrees with Damon's number, as expected.
*March 24, 2016*

**@Engineers**

Nice work, Damon. I like how the engineers always cut to the heart of the problem. Reminds me of the engineer's way to measure the area of an irregular shape. He traced it onto paper, cut it out, and weighed it. Then he weighed 1 cm^2 of paper, and voila! The area was easy.
*March 24, 2016*

**Calculus Applied Integrals**

What similar triangles? The tank has a circular cross-section of πr^2 Work = force (weight)*distance, so figure the weight of a thin slice of water (thickness dy). Then the work done to lift it over the top from depth y is its weight times y. Add up all those work pieces ...
*March 24, 2016*

**Algebra**

As always, draw a diagram. You will see that x/25000 = tan2°
*March 24, 2016*

**mathematics-sequence**

I had a question about 3-tails. Since no one else has offered to help, maybe you should explain how that applies here, rather than just reposting your same question with no additional data.
*March 24, 2016*

**Trig Help**

(b)The period is T=2π/(3π/4) = 8/3 s, so the frequency is 3/8 Hz Now, use T=2π√(L/g) to find L (d) since cos(π/2)=0, you want 3π/4 t = π/2 t = 3π/4 * 2/π = 3/2
*March 24, 2016*

**Trig**

using what I showed you earlier, what do you get?
*March 24, 2016*

**Geometry**

um, what in the above solution, did you not understand?
*March 24, 2016*

**Geometry**

a 4x5 card does not have the same aspect ratio as the 8.5x11 paper enlarging 4 to 8.5 is a scale of 2.125 enlarging 5 to 11 is a scale of 2.2 So, using the smaller scale, 4x5 enlarges to 8.5x10.625 or, 8 1/2 by 10 5/8 trying to enlarge it more will cause the width to exceed ...
*March 24, 2016*

**Trig**

sin(-θ) = -sinθ sec(-θ) = secθ cot(-θ) = -cotθ So, you have (-sinθ)(secθ)(-cotθ) = 1
*March 24, 2016*

**Math**

p * .75 * 1.07 = 67.41 Now just find p.
*March 24, 2016*

**mathematics-sequence**

not sure what you mean by "3-tails" The sequence is clearly just an arithmetic sequence.
*March 24, 2016*

**math**

If there are x kg of the 7.50 nuts, the rest (3-x) are 9.50 So, add up the cost of the amounts used. It must equal the final cost. 7.50x + 9.50(3-x) = 25.00
*March 24, 2016*

**Calculus**

If the ends are x and the other side is y, xy = 25600 So, the cost c(x) = 3*2x + 3/2 y = 6x + 38400/x so, dc/dx = 6 - 38400/x^2 dc/dx=0 when x=80 So, plug that in and find the minimum cost
*March 24, 2016*

**physics**

use T = 2π√(L/g) to get L. Now using that L, replace g with 0.29g to get the new T. .90 = 2π√(L/9.8) L = 0.201 .29*9.8 = 2.842 So, the new T = 2π√(.201/2.842) = 1.671 s ================================== Or, noting that T varies inversely as ...
*March 24, 2016*

**Algebra**

two cases: -2w+7 > 5 -2w > -2 w < 1 -(-2w+7) > 5 2w-7 > 5 2w > 12 w > 6 http://www.wolframalpha.com/input/?i=|-2w%2B7|%3E5
*March 24, 2016*

**Math**

yes it is.
*March 24, 2016*

**MATH**

My bad. You are correct.
*March 24, 2016*

**MATH**

why 1/5? 5 of the 10 digits are even.
*March 24, 2016*

**Math**

h(t) = 3 + 40t - 16t^2 Now just find the vertex of the parabola.
*March 24, 2016*

**Algebra**

8w^2+(8w)(5) = 1102 w = 9.5
*March 24, 2016*

**math**

5000*(1+.07*13) + 5000(1+.03/2)^(2*13) = $16,913.55
*March 24, 2016*

**Algebra**

the integers are 2k and 2k+2 (2k)*2(2k+2) = 160 k(k+1) = 20 20=4*5, so k=4 The numbers are 8 and 10
*March 24, 2016*

**physics**

look at the units: .5 cal/g°C * 10g * 10°C = 50 cal
*March 24, 2016*

**algebra**

first, expand the parentheses, so all the exponents are collected: a^2(ab^3)^2 = a^2 a^2 b^6 = a^4 b^6 b^2(a^2b^2)^2 = b^2 a^4 b^4 = a^4 b^6 Since all the variables have the same exponents, the terms can be added, giving a simple a^4b^6 + a^4b^6 = 2a^4b^6
*March 24, 2016*

**Math**

Just take the fraction of 100 for the group you want: 9/20 * 100 = ?
*March 23, 2016*

**Math**

do you mean 40-4k^3 if so, then for k=2, 49-4*2^3 = 40-4*8 = 40-32 = 8
*March 23, 2016*

**MATHS GP**

ar + ar^3 = 30 ar^5 - ar = 90 I get a=3 and r=2 The GP is 3, 6, 12, 24, 48, 96, 192, 384, ... T2+T4 = 6+24 = 30 T6-T2 = 96-6 = 90 T8 = 384
*March 23, 2016*

**algebra**

Don't knock BASIC. I knew a girl in college who was using it to program a gyroscopically stable table in orbit in 1972.
*March 23, 2016*

**Math**

(6.25-5.50)/5 = 0.15 min/km/mo now use that to form the equation.
*March 23, 2016*

**Math- probabilities**

well, what is the probability that NO ball is white? That is, 2 reds? Then take 1-P(red,red)
*March 23, 2016*

**calculus**

assuming the 80 ft is along the ground, h/80 = tanθ 1/80 dh/dt = sec^2θ dθ/dt when h=6, sec^2θ = 1+tan^2θ = 1+(6/80)^2 = 1.0056 1/80 dh/dt = 1.0056 * 4*π/180 dh/dt = 5.6 ft/s
*March 23, 2016*

**mathematics-discriminant**

hmmm. working with cubics? Gets messy. But, you should be able to find out that the discriminant is Δ = b^2c^2 - 4ac^3 - 4b^3d - 27a^2d^2 + 18abcd For your polynomial, that's just 99225 As wikipedia explains, For a cubic polynomial with real coefficients, the ...
*March 23, 2016*

**math**

add up all the times. If it's about 60 hours, then she's right.
*March 23, 2016*

**Math**

I need 27 2x4 50" long how many feet do I need
*March 23, 2016*

**math**

14*50 - 13*43
*March 23, 2016*

**Math**

Since f is continuous and differentiable on the interval, MVT applies. So, now you just have to find the point(s) c where f'(c) = [f(1)-f(-1)]/[1-(-1)]
*March 23, 2016*

**AP Calculus AB PS**

Oops the volume is v = ∫[1,e] π(4-(lnx+1)^2) dx
*March 23, 2016*

**AP Calculus AB**

A circle of radius R has area πR^2 so, a disc of thickness dx and radius R has a volume v = πR^2 dx Now, if it has a hole in it of radius r, then the hole has volume v = πr^2 dx So, the washer (a disc with hole) has volume v = π(R^2-r^2) dx Sketch the ...
*March 23, 2016*

**AP Calculus AB**

well, you know that a = 40 v = ∫a dt = 40t + a s = ∫v dt = 20t^2 + at + b use the given conditions to find a and b.
*March 23, 2016*

**mathematics**

2(b + 5/4 b) = 81 ... Now that you have b, the area is b * 5/4 b = 5/4 b^2
*March 23, 2016*

**Geometry**

looks ok to me.
*March 23, 2016*

**math**

yes.
*March 23, 2016*

**Calculus**

As usual, draw a diagram. The horizontal distance x (ft) flown is found using x/30000 = tan .94 x = 41077 ft The speed must be changing, or it would be a constant 41077ft/50s = 560 mi/hr. So, since tan(z) = x/30000 sec^2(z) dz/dt = 1/30000 dx/dt To get the units right, 30000ft...
*March 23, 2016*

**Uthan**

If the digits are a,b,c a+b+c=9 100a+10b+c - 198 = 100c+10b+a The numbers 351, 432 and 513 all work
*March 23, 2016*

**algebra 1 or pre algebra**

all reals except -1 and 6 are in the domain. The answers have some typos.
*March 23, 2016*

**Linear Algebra**

The eigenvectors of A are (1,2) and (1,1) So, C = [1,1;2,1] and C^-1=[-1,1;2,-1] C^-1 A C = [3,0;0,2] See http://www.wolframalpha.com/input/?i=%28inverse+{{1,1},{2,1}}%29*{{1,1},{-2,4}}*{{1,1},{2,1}}
*March 23, 2016*

**geometry**

In triangle FGH, g = 8ft, h=13ft, and m=F= 72degrees. Find m<G round to nearest tenth a- 26.2 b- 33.9 c- 72.1 d- 32.5 my answer is b
*March 23, 2016*

**trigonometry - eh?**

Hmmm. this condition cos^3A = sinA × cosA is very strange. It means that cos^2A = sinA 1-sin^2A = sinA sin^2A+sinA-1 = 0 sinA = 0.618 A = .66624 = 38.17° cosA = .78618 Then the other equations are y = .236x .618x = .786y and we're stuck. Ya got me.
*March 23, 2016*

**Geometric progression**

well, I gave you a hint. Try some synthetic division. You know that any rational roots must be found among ±1, ±1/2, ±2
*March 23, 2016*

**Geometric progression**

Geez, guy, you're not gonna work on it at all? a = 30(r-1)/(r^4-1) a = 18/(1+r^3) 30(r-1)(1+r^3) = 18(r^4-1) 30(r^4-r^3+r-1) = 18(r^4-1) 2r^4-5r^3+5r-2 = 0 I'll let you factor that and find that r=2 is a root.
*March 23, 2016*

**math**

too much water
*March 22, 2016*

**matematicas**

hace preguntas aqui
*March 22, 2016*

**Algebra**

it's just a fraction. x = -2/11 y = -5/11 That is the solution. Fractions are numbers, just like 5 and -12. No reason to be afraid of them. and that's should have read 3x+y=-1
*March 22, 2016*

**Algebra**

I assume you meant 3x+y = -1 So, 6x+2y = -2 But, 2y=5x, so 6x+5x = -2 now solve for x and then get y.
*March 22, 2016*

**Algebra**

well, you know that x = 8-2y so, substitute that into the other equation: 3(8-2y) - 4y = 4 Solve for y, then you can get x.
*March 22, 2016*

**Algebra**

if the width is w, then (20-2w)(24-2w) = 320
*March 22, 2016*

**Algebra**

group 1: 160 suits group 2: 3/4 * 160 = 120 suits If the 2nd team made x suits per day, then since it took 4 more days, 160/(x+10) + 4 = 120/x x = 10 extra credit: how many days did the teams work?
*March 22, 2016*

**Algebra**

this is the same as the other one. 150/(55+s) + 150/(55-s) = 11/2 s = 5
*March 22, 2016*

**Algebra**

Let x be the speed from A to B Since time = distance/speed, 120/x + 120/(x+10) = 240/x - 2/5 x = 50 km/hr
*March 22, 2016*

**Math**

(2x^3-9)/(x^3+6x^2+8x) = (2x^3-9) / (x)(x+2)(x+4) = 2 - (9/8)/x + (25/4)/(x+2) - (137/8)/(x+4)
*March 22, 2016*

**Math**

900900949 will round down to 900900900 anything larger will round up to 900901000
*March 22, 2016*

**maths**

if it is rectangular, the area is 1.5 * 3 = 4.5 m^2
*March 22, 2016*

**math**

It could be 5, but then it would be a square, and not really a trapezoid. Since three sides are all 5, it has two parallel sides of length 5. So, if you play around with some designs, you will see that forcing a 3rd side to be also 5, the figure can be low and flat, or square-...
*March 22, 2016*

**Math**

You are correct.
*March 22, 2016*

**math**

the width is 3 times as big, so the length is also.
*March 22, 2016*

**science help pls pls**

If it's a small lake, then all points nearby should have the same climate. If there are prevailing winds, then the spots downwind will be slightly cooler. Other than that, I have no advice to give. If it's a huge lake, I'd guess points at lower latitudes would be ...
*March 22, 2016*

**Math**

only straight line segments
*March 22, 2016*

**Math**

Thanks again😀
*March 22, 2016*

**Math**

She might draw out two of each color. There are only three colors, so on the 7th marble, it must be the same color as two of the others. So, with 7 marbles, she is sure to have 3 the same. How many of each color are in the box doesn't matter. Only the number of colors.
*March 22, 2016*

**Math**

I am having a problem answering this math problem. Andrea has a box of marbles in it. She has seven red marbles, thirteen blue marbles and nineteen yellow marbles. If she reaches in and takes out marbles without looking, what is the fewest number of marbles she will need to ...
*March 22, 2016*

**Math**

2 days is 48 hours, so 48/8 * 400 = 2400 mi
*March 22, 2016*

**Math**

try putting the LS over a common denominator: tanx/(1+secx) + (1+secx)/tanx tanx*tanx + (1+secx)^2 --------------------------- tanx(1+secx) tan^2x + 1 + 2tanx + sec^2x ------------------------------- tanx(1+secx) I ...
*March 22, 2016*

**math**

a(r^4-1)/(r-1) = 30 a + ar^3 = 18 a(1+r^3) = 18 it's easy to see that if a=2, r=2 Does that work on S4? 2*15/1 = 30. Yes So, the GP is 2,4,8,16,...
*March 22, 2016*

**stem and leaf plot**

got no data There are many graphers on line, such as http://www.calculatorsoup.com/calculators/statistics/stemleaf.php
*March 22, 2016*

**math**

That's better.
*March 22, 2016*

**math**

1/4 of 280 is 70 so, what is 3 times that? Did you just guess at 240?
*March 22, 2016*

**math**

recall the Pythagorean Theorem: 2^2 + h^2 = 10^2
*March 22, 2016*

**math**

7!/(3!2!2!) = 210
*March 22, 2016*

**math**

x/8 = cos68°
*March 22, 2016*

**Algebra**

since time = distance/speed, 480/s + 480/(s+20) = 20
*March 22, 2016*

**Algebra**

so? original fraction is x/(x+7) when changed, (x+3)/(x+7+5) = 1/2 2(x+3) = x+12 2x+6 = x+12 x = 6 original fraction is 6/13 new fraction is 9/18 = 1/2
*March 22, 2016*

**math**

The first question asked for a distance. You gave a time. The distance traveled is (4/5.25) * 273 = 208 miles
*March 22, 2016*

**geometry**

the area is A = bh/2 3h * h/2 = 6 3h^2 = 12 h^2 = 4 h = 2 b = 3h = 6 check: 2*6/2 = 6
*March 22, 2016*

**algrbra**

p+5n+10d+25q = 575 p+n+d+q = 40 Now you know that there are 5,7,11,13,17,19,23 as the number of each coin. Since there are no odd cents, you know that p=5. Now you have 5n+10d+25q = 570 n+d+q = 35 or, n+2d+5q = 114 n+d+q = 35 subtracting, we have d+4q = 79 4q must be 20,28,44,...
*March 22, 2016*

**math - Correction.**

On the first try, you were ok to here: y=(log7-log2)/log2 but that's y = log7log2 - 1 On the 2nd try, you went wrong right away: 3(2^y-1) is NOT 6^y-3 it IS 3*2^y - 3
*March 22, 2016*

**math**

why all the useless words? That's what math symbols are for! (8^(y+2)-34(2^(3y)))/√8^(2y+1) = (64*8^y - 34*8^y)/(√8 * 8^y) = 30*8^y / (√8 * 8^y) = 30/√8 = 15/√2 If I got the grouping wrong, fix it and redo the steps. But any other setup will ...
*March 22, 2016*

**math**

The interest would be 380 * .18 * 60/360
*March 22, 2016*

**Tokak**

If AB=8 and DC=5, then if the altitude is h, h = 4sinA = 6sinB h cotA + 5 + h cotB = 8 4 sinA cotA + 5 + 6 sinB cotB = 8 4cosA + 5 + 6cosB = 8 4cosA + 6cosB = 3 solve for A and B. Note that D = (90-A)+90 = 180-A and similarly for C.
*March 22, 2016*

**Maths**

max=10 for 10,20,...,90 min: 19/10 = 1.9
*March 22, 2016*

**Math**

outside: 2(3 2/3 + 4 1/2) = 16 1/3 ft inside (subtract 1/2 ft on each of the 4 sides): 16t 1/3 - 2 = 14 1/3 ft
*March 22, 2016*