Monday
July 6, 2015

Posts by Steve


Total # Posts: 32,118

Math
I'd say 12/15, right?
June 28, 2015

Calculus Partial Fraction
note that x^3-8 = (x-2)(x^2+2x+4) So, your fraction is now x^2 -------------------- (x-2)^2 (x^2+2x+4) As partial fractions, that becomes A/(x-2) + B(x-2)^2 + (Cx+D)/(x^2+2x+4) Placing all that over the common denominator, we have A(x-2)(x^2+2x+4) + B(x^2+2x+4) + (Cx+D)(x-2)^2...
June 28, 2015

math
You need to know how the DJIA is calculated, to figure the effect of any one stock.
June 28, 2015

Math
Using the given formula, your expression is correct, but its value is 3110.50 (D) Expressed correctly, of course, it would be 15,000(0.986975)^(10*12) You must have pushed some buttons wrong if you got (A). Or just guessed...
June 28, 2015

Finance
3000(0.9744^20) = 1785.94
June 28, 2015

Calculus Partial Fraction
well, clearly you can cancel x^2 and you are left with 1 / x(x-2) = A/x + B/(x-2) Now if you place the right side over the common denominator, you have (A(x-2)+Bx)/(x(x-2)) In order for the two numerators to be identical, you need (A+B)x-2A = 0x+1 That is, A+B=0 -2A=1 A = -1/2...
June 28, 2015

Math
could be any of those, depending on the proportion of Microsoft stock in the DJIA.
June 28, 2015

Math
Hmmm. 518400 = (10*9*8)^2 Why did you use that?
June 28, 2015

Math
assuming the order of choice does not matter, 6C4 * 6C4 or, 6C2 * 6C2 = 15*15 = 225
June 28, 2015

Math
P(red,red) = 3/5 * 2/4 You don't really need to record the color, since the bean was not replaced. Unless you have eaten it, you can just look at the two beans drawn.
June 28, 2015

trigonometry
If A is the angle of elevation of the sun, then tanA = height/shadowlength So, height/5 = 5/6 Looks like you need to review the basic trig functions. And always draw a diagram!
June 28, 2015

Math
Looks suspiciously like 30000. Just sayin' ...
June 28, 2015

Maths Problem
Dan finishes in 70 minutes, so Ellen finishes in 75 minutes. If Dan's speed is d m/min Ellen's speed is e m/min So, d = (15/14)e 35e = 35d-300 35e = 35(15e/14)-300 35e = 75e/2-300 5e/2 = 300 e = 120 So, the distance is 120*75 = 9000m You can check to make sure that the...
June 28, 2015

math
16x^2-24x-13=0 16(x^2 - 3/2 x) = 13 16(x^2 - 3/2 x + (3/4)^2 = 13+16(3/4)^2 16(x-3/4)^2 = 22 (x-3/4)^2 = 11/8 x = 3/4 ±√(11/8) or, x = (3±√22)/4 or, eschewing fractions, 16x^2-24x-13 = 0 16x^2-24x+9 = 13+9 (4x-3)^2 = 22 ...
June 28, 2015

maths
I don't believe that one side is only 60cm. Fix that, and just find twice the perimeter, then subtract twice the gate width.
June 28, 2015

Math
recall that 3^4 = 81
June 27, 2015

Finite Math
If there are x Daybrite sets and y Noglare sets, then you want to maximize p=425x+700y subject to x+y <= 400 x >= 70 y >= 160 a good tool is at http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html it will solve and graph the solution
June 27, 2015

Geometry
the two bases of a parallelogram are equal the two bases of a trapezoid are different Bh vs (b+B)h/2 These can only be the same if b=B.
June 27, 2015

Math
well, did you actually try the values to see which are or are not? (0,-1): -1 = 0^2-1? yes now you try the others and we can check your answers.
June 27, 2015

Math
log3(3) = 1 so, 1+log3(x^2) = log3(3) + log3(x^2) = log3(3 * x^2)
June 27, 2015

Math
I'm not Carnak the Magnificent. What was the question, and how did you arrive at your answer? We're willing to provide help, and even answers, but don't make us come up with the questions, too!!
June 27, 2015

calc
so, what about the root test is causing difficulty?
June 27, 2015

calc
just take the integral from 0 to 2.
June 27, 2015

calc
using discs, we have integral[0,π] π sin^2(sin(x)) dx I don't think that can be evaluated with elementary functions. Do you have numeric methods available?
June 27, 2015

math
#1 600000*.9^4 = 393660 #2 16+32*9 = 304 #3 F12 = 89 #4 8*1/√2^5 = √2 #5 Assuming no one received more than one message 2+4+8+16+32 = 62 I suspect a typo in the problem.
June 27, 2015

algebra
variables are represented by letters: x and y numeric constants stand alone: -9 coefficients are numbers multiplying the variables: 4 and 15
June 27, 2015

Math
since the basic function is y=1, and that's not one of the choices, what do you think? Try the various choices to see which one works.
June 26, 2015

math
Since a = 1 r = 2 S4 = 1(2^4-1)/(2-1) = 15 S15 = 2^15-1 = 32768 So, the sum from S5 to S15 = S15-S4 = 32753
June 26, 2015

math
So far, 70% of your score is allocated as follows: .15*74 + .15*96 + .40*60.5 = 49.7 Since that is only 70% of your score, it's equivalent to 49.7/.70 = 70.1%
June 26, 2015

physics
since the sled is not accelerating, the net force acting on it must be zero. So, since the friction is .15*(30*9.8), that is equal to the force acting on the sled.
June 26, 2015

algebra
If there are x fill-in y multiple-choice z long-answer they have given us the following facts: x+y+z = 24 2x+6y+5z = 100 x+y = z Now you can solve for x,y,z
June 26, 2015

math
400$ * 3tickets/5$ = 1200/5 = 240 tickets
June 26, 2015

math
The curves intersect at (-2,2) and (1,-1) so, the area is the sum of all the little horizontal strips between the line and the parabola: ∫[-1,2] (2-y^2)-(-y) dy = ∫[-1,2] 2+y-y^2 dy = 9/2
June 26, 2015

math
x' = y√(y^2+2) so, the arc length s = ∫[0,1] √(1+x'^2) dy = ∫[0,1] √(1+(y^2)(y^2+2)) dy = ∫[0,1] √(y^4+2y^2+1) dy = ∫[0,1] √(y^2+1)^2 dy = ∫[0,1] y^2+1 dy = 4/3
June 26, 2015

physics
the mass of the rocket does not matter. Given a liftoff speed of v, the height h(t) = vt - 4.9t^2 The max height is reached when t = v/9.8, so we have v(v/9.8) - 4.9(v/9.8)^2 = 100 v = 44.27 m/s Or, you could just use the formula for max height h = v^2/2g and get v^2/19.6 = ...
June 25, 2015

Probability
Assuming a uniform population, the 1st person has a birthday. The 2nd has the same birthday with probability 1/365 same for the 3rd. So, ...
June 25, 2015

DTM
you never have said how many gallons (or liters) of gas (or petrol) have been used. Tough to figure mileage (or kmage) without that.
June 25, 2015

DTM
.50$/km * 100km/day = 50$/day not sure just what it is you want to know.
June 25, 2015

Algebra
If there were x more meets to go, and they won them all, then, since the wins = the losses 2+x = 10-2 take it from there. Note that the value of x is not the answer.
June 25, 2015

Math
I already see one error: gt = ln(v+1)
June 25, 2015

Math
dv/dt = g(1+v) dv/(1+v) = g dt ln(1+v) = gt 1+v = e^(gt) + c v = e^(gt) + c (diferent c) v(0) = 0, so c = -1 v = e^(gt)-1 now, v = ds/dt, so s = 1/g e^(gt) - t + c now, e^(gt) = v-1, so s = 1/g (v-1) - t + c since v = e^(gt)-1, ln(v)+1 = gt t = 1/g (ln(v)+1)) and so s = 1/g (v...
June 25, 2015

Math
.9*77 + .1*67 = 76 Look like it won't hurt too much. 1 point.
June 25, 2015

Algebra
revenue is price * quantity, so R(x) = x*p(x) = x(-.16x+320) = -.16x^2 + 320x Now just find the vertex of that parabola to locate maximum revenue.
June 25, 2015

Algebra
I think you are missing a minus sign on the x^2 term, since g = -32 ft/s^2 h(x) = 1/42 (-16/42 x^2 + 72.7x) = x/42 (-16/42 x + 72.7) h=0 when x=0 (ball is hit), and when x = 190.8 (ball lands) The symmetry of a parabola means that the ball is at its highest midway between the ...
June 25, 2015

math gr. 10
Two good solutions are provided by Reiny and MathMate in the related questions below.
June 25, 2015

maths
well, if y = sum(a_n x^n) y' = sum(n*a_n x^(n-1)) y" = sum(n(n-1)*a_n x^(n-2)) so, from the DE, we have sum(n(n-1)*a_n x^(n-2)) + 3x^2*sum(n*a_n x^(n-1)) - x*sum(a_n x^n) sum(n(n-1)*a_n x^(n-2)) + 3sum(n*a_n x^(n+1)) - sum(a_n x^(n+1)) sum(n(n-1)*a_n x^(n-2)) + sum((...
June 25, 2015

Math
polar can get kind of complicated, but this one's a piece of cake: y = t+4, so t = y-4 x = (y-4)^2 + 4(y-4) + 8 Now expand it out and note that it's just a parabola.
June 25, 2015

Math: Compounded Interest
just use your formula. For quarterly, that is 200(1+.05/4)^(4*1/4) = 202.5
June 25, 2015

Math - thx Reiny
Good catch. I felt vaguely uneasy with the way things worked out, but was in a hurry. No doubt Justine caught the slip on her own...
June 25, 2015

Math
r = 1/(3-4sinθ) (a) see http://www.wolframalpha.com/input/?i=r+%3D+1%2F%283-4sin%CE%B8%29 (b) r = 1/(3-4sinθ) r(3-4sinθ) = 1 3r - 4rsinθ = 1 3√(x^2+y^2) - 4y = 1 3√(x^2+y^2) = 4y+1 3(x^2+y^2) = 16y^2+8y+1 3x^2 - 13y^2 - 8y = 1 3x^2 - 13(y^2 - 8/...
June 25, 2015

math
maybe you should lie on the floor and kick your feet, too. Beats me what would come next. What kind of material are you studying, that they'd drop a sequence like that on you? Or are you just wasting everybody's time with lottery numbers?
June 25, 2015

physics
You know, when you log on here you see all these posts with subjects like math, science, psychology, English, etc. Why do you think that Cowdray Park will be interpreted as a school subject? work = force * distance So, just plug in your numbers.
June 25, 2015

advanced algebra
how about you provide the function, instead of naming a file we cannot see? Is it p(t) = a*e^(kt) with suitable values of a and k?
June 24, 2015

Math
the properties of logs are the same as those of exponents. √2 = 2^1/2 because √2 * √2 = 2 and 2^a * 2^b = 2^(a+b) 2^1/2 * 2^1/2 = 2^1 = 2 And, 2^-n = 1/2^n so, 1/√2 = 2^-1/2
June 24, 2015

Math
4x - e^(-(4x-y+3)) = -e^(-2) e^(-(4x-y+3))= 4x + e^(-2) -(4x-y+3) = ln(4x + e^-2) 4x-y+3 = -ln(4x + e^-2) y = 4x+3 + ln(4x + e^-2)
June 24, 2015

Math
since y(2) = 2, e^(2-2) = -2+c 1 = -2+c 3 = c So far, so good. e^(x-y) = -x+3 x-y = ln(-x+3) y = x-ln(-x+3) Somehow you got an extra "-" sign in there
June 24, 2015

6TH GRADE MATH
assuming in and out mean up and down, then I get -2-19+7 = -14 You have the bait 10 feet above the water!
June 24, 2015

math
θ=42°
June 24, 2015

Math - oops
Oops. I added, instead of subtracting. The final answer, of course, is -1/2, as shown above.
June 24, 2015

Math
log(√x) = 1/2 log(x) since log(x^n) = n log(x) So, what you have is √36 = 6, so √72 = 6√2 So, assuming by log2 you mean log2, log26 + log26 + log22 but log22 = 1, so that is = 2log26 + 1/2 Now, what is log26? You don't have a log2 button on your ...
June 24, 2015

physics
Unless the pilot can track a speeding bullet, I don't see how he can take any of those measurements. I guess he could turn the gun backwards and fire it when passing over an observer. If the observer sees the bullets come straight down, the speeds are ok.
June 24, 2015

physic pls help
how long does it take to fall 45m? 4.9t^2 = 45 t = 3.03 seconds So, how fast do they have to be moving to cover the 15m in 3 sec? 5m/s How fast is 5m/s in terms we can really relate to? That's 100m in 20 sec. Great athletes cover 100m in about 10 seconds, so it's only ...
June 24, 2015

statistics
ummm that would be .3 + .12 * 1.3 = ?
June 24, 2015

physics
just solve for t in 24 + 24.5t - 4.9t^2 = 0
June 24, 2015

Physics
the max height is (v sinθ)^2/19.6 the speed at time t is √(Vx^2+Vy^2) = √((v cosθ)^2 + (v sinθ - 9.8t)^2) The speed at max height is just Vx = v cosθ So, find t when h(t) is half the max height. That is, when vsinθ t - 4.9t^2 = (v sinθ...
June 24, 2015

Algebra
Suppose there are x price decreases. so, price is 400-x membership is 300+3x revenue is thus (400-x)(300+3x) = -3x^2+900x+120000 So, just find the vertex of the parabola to determine price and max revenue.
June 24, 2015

math
friction coefficients? mass of man? force of man's steps?
June 23, 2015

English
2 and 4 are the same 1 and 3 are almost self-contradictory. If he kept in touch, that means he got in touch on a regular, continuing basis. You can't do that every day. So, 1 and 3 are really not good English.
June 23, 2015

algebra
if x is at 5%, the rest (30000-x) is at 9%. So, you want x in .05x + .09(30000-x) = .08(30000)
June 23, 2015

algebra
x^4 + 2x^3 - x^2 - 2x x(x^3 + 2x^2 - x - 2) x(x^2(x+2)-(x+2)) x(x^2-1)(x+2) x(x-1)(x+1)(x+2) I expect you can take it from there, yeah?
June 23, 2015

maths
if cot x = 3/4 sec x = 5/3 csc x = 5/4 So, plug in the values and see whether it's true.
June 23, 2015

maths
So, is it ever true? tanθ/(1+tan^2θ) = sinθ/cscθ tanθ/sec^2θ = sin^2θ sinθ cosθ = sin^2θ sinθ(cosθ-sinθ) = 0 θ = π/4
June 23, 2015

maths
If you can't spell theta you might as well just use x. secθ = 5/4 so, sinθ = 3/5 cscθ = 5/3 tanθ = 3/4 tanθ/(1+tan^2θ) = sinθ/cscθ (3/4)/(1+9/16) = (3/5)/(5/3) (3/4)/(25/16) = 9/25 3/4 * 16/25 = 9/25 12/25 = 9/25 Hmmm. I suspect a ...
June 23, 2015

Guru found Singh
If I said A product of two integers is 10. If one number is 5, find the other number. could you find the other? Follow the same step here.
June 23, 2015

Science
a = v^2/r, so .18 = v^2/5 Now just find v.
June 23, 2015

Differential Equation
as you know, |ai+bj| is √(a^2+b^2) and ai+bj + ci+dj = (a+c)i+(b+d)j so what do you get?
June 23, 2015

vectors
two sides are <8,6,-4> and <9,10,14> The cross product is <124,-148,26> Its magnitude 194.823 is twice the area of the triangle.
June 23, 2015

maths
well, all four angles add up to 360, so 30+50+d+d = 360 . . .
June 23, 2015

statiSTIcs
52 is 2 std above the mean of 44. So, look up Z=2 in your table, and subtract that from 1. Or, mosey on over to http://davidmlane.com/hyperstat/z_table.html and enter 2 in the "Above" box and it will calculate the Z value and show the tail of the graph.
June 22, 2015

Calculus
well, recall what you were told: The price(in dollars) p,and the quantity sold x obey the demand equation p=-1/10x+150 You found that maximum revenue R occurs at x=750, so p = -75+150 = 75
June 22, 2015

algebra
c = k-4 c+2 = (k+2)/2 + 11 c = 24
June 22, 2015

math
AB = 12, BC = 4, CD = 7, and DA = 15 Start off my assuming that the largest number is the whole line. That might not be so, but it's a good place to start. B must be to the right of C, since BC < CD That means we have ACBD. Check: AC=8 CB=4 BD=3 You just have to play ...
June 22, 2015

algebra
just find t when 5422(1.037^t) = 29000000 (I dropped 3 zeros on each side) 1.037^t = 5348.57 t = log(5348.57)/log(1.037) It'll be a while
June 22, 2015

algebra
You don't say whether the dividing fence is to be parallel to the river or not. If not, then let x be the length of the side parallel to the river. Then you have x+3y = 4700 so, x = 4700-3y The area is a = xy = (4700-3y)y = 4700y - 3y^2 The vertex of this parabola is at (...
June 22, 2015

algebra
same as the others. Give it a try. period
June 22, 2015

algebra
this is just like the river field. Why do you insist on saying "comma" and then writing the number with the comma? question mark
June 22, 2015

algebra
if the side parallel to the river is x, and the other two sides are y, you have x+2y = 9000 the area a = xy = (9000-2y)(y) = 9000y-2y^2 The vertex of this parabola is where you have maximum area. That is at y = 9000/4 You have y, so you can get x, and can find the area.
June 22, 2015

Algebra
why all the words, when you have the symbols? demand quantity at price x is p(x) = 1/40 x + 19000 The cost is C(X) = 15450x + 20000 (a) So, the revenue (price * quantity) is R(X) = xp(x) = 1/40 x^2 + 19000x (b) P(x) = R(x)-C(x) = (1/40 x^2 + 19000x)-(15450x + 20000) = 1/40 x^2...
June 22, 2015

Geometry
42 u2004-42-42-42-00_files/i0060042.jpg
June 22, 2015

Math
see related questions below
June 22, 2015

math
your answer is correct. Why all the nonsense below it?
June 22, 2015

Math
If the number of 37,50,58-in tv's are x,y,z, then x = 2(y+z) y = z 1800x+2000y+4800z = 168000 Now just solve the three equations.
June 22, 2015

physics
F = ma = 1.2*10^3kg * (20m/s)/(5s) = 4.8*10^3 kg-m/s^2 = 4.8*10^3 N
June 22, 2015

Algebra
If the number of 37,50,58-in tv's are x,y,z, then x = 2(y+z) z = ? (which are equal?) 1800x+2000y+4800z = 168000 Fix the second condition, and then solve the three equations.
June 22, 2015

algebra
√42 By the way, your files cannot be seen anywhere except on your computer.
June 22, 2015

programming ( qbasic)
I did google searches for qbasic input to find how to do input and print qbasic math to see how math was done. It also showed the DIM statements and a FOR loop qbasic strings to find string functions like Val and CHR and ASC
June 22, 2015

programming ( qbasic)
DIM WORD AS STRING DIM SUM AS INTEGER INPUT "Enter a word: ", WORD$ SUM = 0 FOR N=1 to LEN(WORD$) SUM = SUM + ASC(MID$(WORD$,N,1)) NEXT N PRINT "Word value: ",SUM google is your friend. I have never used qbasic, but in about five minutes I found enough code...
June 22, 2015

Physics
you assumed g/min was gallon/minute Not so. It is grams/minute So, keeping track of the units, you want to convert volume to time: 196gal * 231 in^3/gal * (2.54cm/in)^3 * 1g/cm^3 * 1min/g = 741940 min = 1.41 yr Hmmm. check my math or your supposed answer
June 22, 2015

Math - not
I'm sure an acronym is not what you are after. An acronym is a word whose letters come from the words of a phrase represented, such as LASER - Light Amplification by Stimulated Emission of Radiation Maybe you are supposed to write a list using the letters of the word as in...
June 22, 2015

mathematics
type that into google or, what the heck -- use your calculator stop wasting time here with such nonsense.
June 22, 2015

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