Monday
May 30, 2016

Posts by Steve

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

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