Thursday
July 2, 2015

Posts by steve


Total # Posts: 32,074

Algebra Word Problem
if there are x price increases, the revenue is (95-x)(100+x) That is just a parabola. Its vertex represents maximum revenue.
April 28, 2015

Calculus
your logic and your answer are correct.
April 28, 2015

Calc
wold that not be just the integral of C' from 3500 to 8500? Just use the power rule for each term.
April 28, 2015

Calculus help??
f(x) = ∫[0,x] 2πu du df/dx = 2πx you are correct. I suspect that those choices belong to a different problem, or that there is a misprint in this one.
April 28, 2015

Calculus I
The question is, how many can you sell at $10? Let's say it's 1000. Then if there are x price reductions, you can sell 1000+500x So, the revenue will be (1000+500x)(10-x) The cost is 3000+2(1000+500x) profit is revenue - cost. Use your real value instead of 1000, and ...
April 28, 2015

Math Check
both right
April 28, 2015

Math Check
Both look good to me.
April 28, 2015

math
the left side is also just a difference of two squares, so ((a-3)+(a-2))((a-3)-(a-2)) = (2a-5)(-1) so, you have 5-2a = 5 a = 0
April 28, 2015

Math
it's a problem in exponential growth similar ones in exponential decay are things like radiocarbon dating, where the amount of carbon-14 diminishes each year by a certain small percentage.
April 28, 2015

Math
after t minutes, there are 2^(t/15) bacteria. So, find t when 2^(t/15) = 10000 t/15 log2 = log10000 t = 15 * (log10000/log2)
April 28, 2015

math
if the side of the base is s, then you know that 10s^2 = 810 The total area is the base (x^2) and 4 sides, each of area 10x.
April 28, 2015

math
the base is 18*18 each side is a triangle of base 18 and height 12, so the faces have area 4*(18*12/2) SO, just do the math.
April 28, 2015

Algebra
3x = 7*8/21 x+2 = 5*20/10 That should get you started
April 28, 2015

math
v = Bh so, 9B = 2025
April 28, 2015

chemistry
You Can Get Your All Chemistry and other subjects questions Solved just Visit: http://www.myassignmenthelp.net/data-structure-assignment-help.php
April 28, 2015

5th grade (math)
the difference between two numbers is found by subtraction: 13 1/10 - 12 1/2 = 12 11/10 - 12 5/10 = 6/10 or 3/5
April 28, 2015

math
v = 40mm * 25mm * 2mm = 2000 mm^3 so, the weight is 2000 mm^3 * .0005oz/1mm^3 = 1oz
April 28, 2015

English
In Edgar Allan Poe’s poem “The Bells,” how does the tone change from the beginning to the end? from melancholic to scary from cheerful to sinister from peaceful to frenetic from hopeful to embittered
April 28, 2015

English
"The Cask of Amontillado" Poe's use of a(n) _________________ narrator to tell the story heightens the uncertainty and sense of horror felt by the reader.
April 27, 2015

College Algebra
well of course the vertex is the maximum area. The parabola represents the area, right? And you are correct in your final answers, with the exception that when x=200 and y=125, 4xy = 4*200*125 = 100,000
April 27, 2015

College Algebra
well, if each pen is x by y, then the vertical lines have length x, and the horizontal lines have length 4y, then we know 5x+8y = 2000 then the area is a = 4xy = 4x(2000-5x)/8 = 1000x - 5/2 x^2 This just a parabola, and its vertex will be the maximum area. Work it out, and you...
April 27, 2015

Math
sums are terms separated by + or - signs products consist of two or more factors multiplied. So, what do you say?
April 27, 2015

math
then
April 27, 2015

Inequalities Interval Notation
After you get a bit of practice with this kind of stuff, you can feel confident using what you know about the graphs of polynomials. (2 + x)(5 + x)(4 - x) < 0 You know this is a cubic, with three roots. The graph crosses the x-axis at each root. So, pick a very large ...
April 27, 2015

Math help!
of course the are will be minimum if the width of length is zero. But that's not what you want, I'm sure. So, you want the arrangement of fences which will produce the maximum area. You don't say how the area is to be divided. Is the beet garden enclosed by the ...
April 27, 2015

science
Try To find Your Answers at below Link http://www.myassignmenthelp.net/chemistry-assignment-help.php
April 27, 2015

math
#1-3 are very poorly worded. Whoever phrased them like that ought to be shot. #1 x and y have equal rates of change #2 y has the greater rate of change. #3 clearly y changes faster. Heck, they told you that in just so many words. #4 ok #5 you gave the values for y=x^2 But the ...
April 27, 2015

C++ Programming
why don't you google C++ and some of those key concepts? You will find many code snippets illustrating the syntax.
April 27, 2015

Math
the average rate of change is just f(π/8)-f(π/10) ------------------- (π/8 - π/10) Now just plug and chug. It's just the slope of the line joining the two points on the curve.
April 27, 2015

Math
the divisor is a factor if the remainder is zero Just as you know that 5 is a factor of 35 because 35/5 has zero remainder. For example, (2x-1)(x+2)(3x+7) / (x+2) = (6x^3+23x^2+15x-14)/(x+2) we know that the remainder is zero, because we constructed it that way. To make that a...
April 27, 2015

AP Calc B/C
we are told that p doubles every 35 years. That means p = Po * 2^(t/35) Each year it increases by a factor of 2^(1/35) = 1.02, or 2% per year.
April 27, 2015

Calculus
The curves intersect at x = ±1.18. So, using symmetry, the area is a = ∫[0,1.18] cos(x) - (x^2-1) dx Those are all easy integrals, so just plug and chug.
April 27, 2015

Algebra
If the classes are a,b,c,d, then b = a+60 c = 2a-50 d = 3a a+b+c+d = 1424 a+(a+60)+(2a-50)+(3a) = 1424 7a + 10 = 1424 7a = 1414 a = 202
April 27, 2015

math
2-2sin^2-sin-1=0 2sin^2+sin-1 = 0 (2sin-1)(sin+1) = 0 sin = 1/2 or -1 sin = 1/2 at pi/6 and 5pi/6 sin = -1 at 3pi/2 Better check your factoring. Your angles are correct for the values you obtained, but those values had the wrong signs, and hence, the wrong sines :-)
April 27, 2015

Calculus
y = √(x^3+2) y' = 3x^2/(2√(x^3+2)) y' = (6x)(2√(x^3+2)) - (3x^2)(6x^2)/(2√(x^3+2)) ----------------------------------------- 4(x^3+2) 24x(x^3+2)-18x^4 ------------------------ 8(x^3+2)^(3/2) 3x(8(x^3+2)-6x^3) ---------------- 8(x^3+2)^(3/2) 3x(...
April 27, 2015

Precalc-functions
y = 2/3 x + 5 y-5 = 2/3 x x = 3/2 (y-5) so, f^-1(x) = 3/2 (x-5) as with all polynomials, the domain is all real numbers.
April 27, 2015

Math 222
why not just use conventional math notation? 5x^2-9x+2 = 0 the discriminant is b^2-4ac = 81-40 = 41 Now just use that in the quadratic formula. Since the discriminant is positive, there are two real solutions: x = (9±√41)/10
April 27, 2015

Math
I think it is (C) Roll that rectangle along the horizontal axis, and fold over the ends.
April 27, 2015

Math
looks correct to me.
April 27, 2015

Algebra 222
{w|w > 1} = (1,∞) {w|w greater than less than 5} = {w|w≠5} = {-∞,5)U{5,+∞)
April 27, 2015

geometry
the distance out from the dock for an angle θ is just d = 14 cosθ So, the change in distance is just 14(cos 9.2° - cos 14.1°)
April 27, 2015

math
the arc length of the sector is s = rθ = 36(210/360)(2π) = 132 That becomes the circumference of the base of the cone. So, the radius of the base of the cone is 132/(2π) = 21 Now look at the cone from the side. Its height h is given by 21^2 + h^2 = 36^2 Now you ...
April 27, 2015

math
do you not have a simple formula for loan amortization? Just plug in the numbers...
April 27, 2015

math
p + 3p = 48 now you can find pink, and red = 3 times that.
April 27, 2015

algebra
4/1800 = x/8400 m/k = m/n * n/k = 1/5
April 27, 2015

Chemisrty
you are reducing the concentration by a factor of .2/6 So, you need to increase the volume by a factor of 6/.2
April 27, 2015

PCM
you can't get offline stuff from any web site...
April 27, 2015

Business Math
You want x, where 2200(1+.08x) = 1960(1+.10x)
April 27, 2015

Math
yes. Since sinθ is negative in QIII and QIV, that should make it clear that they only want one solution. sin(.2054) = .204, you want QIII, so θ=π+.2054
April 26, 2015

math
correct.
April 26, 2015

math
since the horizontal distance is the same for all three streets, the steepest street will be the one with the greatest vertical rise. steepness = vertical/horizontal change
April 26, 2015

Math
well, since 3 cm is 3 times as big a 1 cm, the real length will be 3 times as big as well.
April 26, 2015

Math
For a fair coin, the number would be 150 * 1/2 = 75 But, we just went through a lot of work to discover that our coin has a probability of 17/30 for getting heads. So, with that coin, 150 tosses should come up with 150 * 17/30 = 85 heads, not 75.
April 26, 2015

Math
f=w+6 p=w-3 f+p+w = 27 (w+6)+(w-3)+w = 27 3w+3 = 27 3w = 24 w = 8 So, the wrist has 8 bones. Now find the values for the other two parts of the hand.
April 26, 2015

calculus
4x dx/dt + 3y^2 dy/dt = 0 Now just plug in your values and solve for dx/dt.
April 26, 2015

Maths
well, you didn't say which side is the base, and which are the two equal sides. I will assume A is the vertex between the two equal sides. In that case, AB = AC, so (A): (4x-3)/15 = (x+3)/5 I assume you can now work out the rest. If I got the two equal sides wrong, then ...
April 26, 2015

math
Let y = x+28 Then xy=7 x(x+28) = 7 x^2+28x-7 = 0 x = -14±√203 I suspect a typo.
April 26, 2015

math
s(t) = t^3/3 - 12t^2/2 + 36t Strange, saying 12t^2/2 rather than 6t^2, but hey ... Assuming "moving to the right" means s(t) is increasing, then we just have to find when ds/dt > 0. That is, t^2 - 12t + 36 > 0 Hmmm. Something tells me you had a typo, and it was...
April 26, 2015

math
do you have some graph paper? pick any value for x, and calculate y. The easiest value to use is x=0. Then y=3. So, the point (0,3) is on the graph. For y, if you pick and even value, you will have a fraction for x, so pick any odd value, say, y=1. Then x=1, and (1,1) is on ...
April 26, 2015

Math
42 cm^2
April 26, 2015

math
so, did you use the product rule as advised? v = x^2 h dv/dt = 2xh dx/dt + x^2 dh/dt Now just plug in your values to find dv/dt. Note that dv/dt does not actually depend on h at all, just dh/dt.
April 26, 2015

Math 222
F = mv^2/r Fr = mv^2 Fr/v^2 = m
April 26, 2015

Math
-(3a-7b)/(2a) + (5a-4b)/(3a) + 3 The common denominator is (2a)(3a), so we have for the numerator -(3a-7b)(3a) + (5a-4b)(2a) + 3(2a)(3a) = 19a^2+13ab so, our final fraction is (19a^2+13ab)/6a^2 = (19a+13b)/(6a)
April 26, 2015

Calculus 2
I think it is (n^(1/n)-1)^n Using the ratio test, T(n+1)/Tn = ((n+1)^(1/(n+1))-1)^(n+1)/(n^(1/n)-1)^n If you can show that that ratio is less than 1, you're home free.
April 26, 2015

Calculus
the average value of f(x) on [a,b] is ∫[a,b] f(x) dx ----------------------- b-a f' = 3x^2-6x f = x^3-3x^2+4 so, you want ∫[-1,3] x^3-3x^2+4 dx -------------------------- 3 - (-1) which I'm sure you can do.
April 26, 2015

Business Math Please Help me
there is a nice discussion here. It should enable you to come up with the result you want. http://en.wikipedia.org/wiki/Economic_surplus
April 26, 2015

Physics
The two components of the distance between them is x = 4√3 y = 4 (a) if the velocity is v, then the two components are (using g=10 for simplicity) x(t) = vt y(t) = -5t^2 so, for the apple to travel 4√3 meters out, it will take 4√3/v seconds. It must fall 4 ...
April 26, 2015

Calculus
y'=x∛y The tangent line at (2,8) is thus y-8 = 4(x-2) y'=x∛y y^(-1/3) dy = x dx 3/2 y^(2/3) = 1/2 x^2 + c y^(2/3) = 1/3 x^2 + c since y(2) = 8, 4 = 4/3 + c c = 8/3 y^(2/3) = (x^2 + 8)/3 The domain is clearly where x^2+8 >= 0, or all reals. for minimum ...
April 26, 2015

math
what difference does it make how much water is in the tank? Are we to assume maximal packing, or just a rectangular lattice of spheres?
April 26, 2015

Engineering Physics 1
you know the height function, so set them equal. Let's use g=10 for convenience: 10t-5t^2 = 15(t-1)-5(t-1)^2 t = 4/3 that is, 1/3 s after the 2nd arrow takes off. You can figure the height, I guess.
April 26, 2015

integral
let u = 4+x du = dx x = u-4 3x/√(4+x) dx = 3(u-4)/√u du = (3u-12)/√u du = 3u^(1/2) - 12u^(-1/2) du Now it's just easy power rule stuff.
April 26, 2015

math
45 * (8/3)^2
April 26, 2015

Calculus 2
well sum of 1/n^2 converges, and cos^2(n)/n^2 <= 1/n^2
April 25, 2015

Math
18sin^2x + 3cosx - 17 0 18 - 18cos^2x + 3cosx - 17 = 0 18cos^2x - 3cosx - 1 = 0 (6cosx-1)(3cosx+1) = 0 cosx = 1/6 or cosx = -1/3 x = 1.40 or 2π-1.40 x = π-1.23 or π+1.23
April 25, 2015

Calculus 2
huh? They told you that p=e
April 25, 2015

Calculus 2
since 1/n^p converges if p > 1, 1/n^e converges
April 25, 2015

Math
my other thought was stratified because of the grouping and selection
April 25, 2015

Math
You want to find out what the favorite hot lunch in the school cafeteria is among the high school students. At an assembly for the whole school, you decide to survey all students who are sitting on the end of their rows in the auditorium. What type of survey are you conducting...
April 25, 2015

Math
in order to find out what the best restaurant is in town you call 25 of your friends at random. what type of survey is this? a- biased b-random c-systematic d-stratified my answer is biased because you may pick at random but they are all still your friends.
April 25, 2015

Pre-Calculus
nope. consider the fraction of the job done in one hour: 1/3 + 1/b = 1/2 In this case you got lucky, since indeed 1/3 + 1/6 = 1/2.
April 25, 2015

Calculus
circle: a = pi r^2 da/dt = 2pi r dr/dt = 2pi * 10/(pi-1) square: a = s^2 da/dt = 2s ds/dt = 2*10/(pi-1) da(circle)/dt - da(square)/dt = 20/(pi-1) (pi-1) = 20 in^2/s
April 25, 2015

Calculus
f is decreasing when f' < 0 f' = 2x-27 so, when is 2x-27 < 0?
April 25, 2015

Math
no you haven't the 274 is 275 though
April 25, 2015

Math
218 sorry
April 25, 2015

Math
What is the 1st quartile of the following data set? 2745,257,301,218,265242,201 a-201 b-218 c-257 d-270 my answer would be 28 because 201 would be the minimum.
April 25, 2015

Calculus
y = 3x^2 + 1 dy/dt = 6x dx/dt so, 3 = 6*2 dx/dt dx/dt = 1/4
April 25, 2015

trigonometry pls help
you saying that you cannot evaluate 18tanθ when given θ? the area is 1/2 bh = 18y since tanθ is increasing, the area will be greater when θ is greater.
April 25, 2015

physics
the acceleration was (-24m/s)/6s = -4m/s^2 s = vt - 1/2 at^2 = 24*6 - 2*6^2 = 144-72 = 72 m
April 25, 2015

PHYSICS answer check
a is usually used for acceleration, which is m/s^2. You ought to have used v, which in fact was entirely omitted: 50000*3 = 60000v v = 2.5 m/s Your answer was correct, but the "a" was misleading.
April 25, 2015

Physics - eh?
360 what?
April 24, 2015

Algebra
a=7 b = -5 c=0, so x = (5±√(25-0))/14 = (5±5)/14 x = 0 or 5/7 But then, we saw that just by factoring: x(7x-5) = 0
April 24, 2015

Algebra
(x^2-4)(x^2-25) = 0 (x-2)(x+2)(x-5)(x+5) = 0 . . .
April 24, 2015

Intermediate Algebra
150/1000 = x/5280
April 24, 2015

Algebra
2(9a-6)^2=11(9a-6)+63 2(9a-6)^2-11(9a-6)-63 = 0 If you rewrite this using u = 9a-6, you just have 2u^2-11u-63 = 0 (2u+7)(u-9) = 0 u = -7/2 or u=9 That means 9a-6 = -7/2 18a-12 = -7 18a = 5 a = 5/18 9a-6 = 9 9a = 15 a = 5/3
April 24, 2015

geometry
Nothing is wrong. The chord is 12 units from the center of the circle.
April 24, 2015

geometry
No idea where B is. arc length is radius time central angle. m<DEC = 2*m<DAC m<DEA = 180 - m<DEC = 180-124 = 56 arc AD = radius * 56 = AC*28*(pi/180)
April 24, 2015

Calc 1
basic stuff. f(x) = lnx/x^-6 limit is same as (1/x)/-6x^-5 = -x^4/6 = 0 f'(x) = x^6 * 1/x + 6x^5 lnx = x^5 (1+6lnx) so, f'=0 when x = e^(-1/6) f" = x^4 (11+30lnx) x^4 is always positive, so, f" > 0 when lnx > -11/30, or x > e^(-11/30) I expect you ...
April 24, 2015

Calc 1
take derivatives, and the limit is the same as that for (1/x)/(5π cos5πx) = (1/1)/(5π*-1) = -1/(5π)
April 24, 2015

Math
8C5 = 8C3 = 8*7*6 / 1*2*3 = 56 Note that 8C5 = 8C3 because 8*7*6*5*4/1*2*3*4*5 = 8*7*6/1*2*3 The extra two factors 4*5 cancel out.
April 24, 2015

Math
The first 4 are all ok. The last one is the Fibonacci Sequence, where each term is the sum of the two previous terms. It goes 1,1,2,3,5,8,13,21,34,55,... Your constant d=3 is just based on the terms 5,8 but clearly does not hold for the earlier terms.
April 24, 2015

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