Monday
October 20, 2014

Posts by Steve


Total # Posts: 25,943

math
If all we are interested in is the number of shares, all the info about their value is just noise. a+b = T a=79 79+b = T b = T-79 a = T-b b = T-a and so on
October 16, 2014

Math
the list must have pairs, working in from the ends. The only such lists I see are C and D
October 16, 2014

math
the definition of π is the ratio of the circumference to the diameter of a circle. So, C/d = π The diameter is twice the radius So, C/2r = π C/r = 2π
October 16, 2014

Algebra
between the two, they cover the 230 ft. So, after Belle has been swimming x seconds, 2x + 5(x-10) = 230 2x + 5x - 50 = 230 7x = 280 x = 40
October 16, 2014

math
Looks unchanged to me. Still A'B
October 16, 2014

Algebra
this is another just like the others. The relative speed of the 2nd car is 10 km/hr faster. In two hours, the 1st car has gone 60km. So, it takes 6 hrs for the 2nd car to catch up. By that time, the 1st car has been going for 8 hours. Or, as Reiny showed you, you want to find ...
October 16, 2014

Math
your inequality is correct. So, 750+35w > 1200 35w > 450 w > 12.8 Since she probably doesn't get paid till the end of the week, that means she'll need to work at least 13 more weeks to have the $1200 saved up.
October 16, 2014

Math algebra Help please
so the area is increased by a factor of 6^2
October 16, 2014

Math
Where's the product. You should have said (2+(n/3))*(a-4) I can see where it might also be (2+n)/3 * (n-4) That assumes that the two numbers are the same. If not, it'd be (2+a)/3 * (b-4)
October 16, 2014

Algebra
the trains are separating at 70+50=120 mi/hr When the 2nd train left, they were already 50 miles apart. So, the remaining 300 miles will take 300/120 hours. Add that to the original hour head-start.
October 16, 2014

Science
which disorder?
October 16, 2014

Math
where did you get the 4? the quotient of a and b is a/b. So, you have the quotient of 2 and the sum of a number and 5 2/(x+5)
October 16, 2014

science
the event is indeed the formation of the rock. From that point on, the strontium in the rock decays, allowing determination of the age of the rock.
October 16, 2014

Physics
Magnetic field = permeability x turn density x current For a solenoid of length L =0.745m with N =350 turns, the turn density is n=N/L turns/m. If the current in the solenoid is I =1.69 amperes and the relative permeability of the core is k =1( air) then the magnetic field at ...
October 16, 2014

Math
n = 2d-1 5n+10d = 855 now crunch the numbers.
October 16, 2014

Algebra
the real problem, as I see it, is that you don't know the formula. How can you be given a problem about perimeters and not have learned how the perimeter is figured?
October 16, 2014

Algebra
you know the perimeter is 2(width + length) So, now you are told that l = 3w and that 2((l+4)+(w-1)) = 102 since l=3w, that means 2((3w+4)+(w-1)) = 102 3w+4+w-1 = 51 4w+3 = 51 4w = 48 w = 12 Now you can figure the original length.
October 16, 2014

Algebra
2((3w+4)+(w-1)) = 102 w=12 2((2x+6)+(3x-1))) = 90 x=8 So, on both problems, you can now figure the answers needed.
October 16, 2014

Calculus
I find it a lot more readable just to use y', instead of all those dy/dx. And, there's no reason to rearrange the equation. arctan(x^5y)=xy^5 1/(1+x^10y^2) (5x^4 + x^5y') = y^5 + 5xy^4y' 5x^4y/(1+x^10y^2) + x^5y'/(1+x^10y^2) = y^5 + 5xy^4y' Now collect ...
October 16, 2014

Algebra
a = 2g-6 5a = 8g Now just solve for a.
October 16, 2014

Math
well, it's clear that cosθ = -1/2 There will be solutions in QII and QIII
October 16, 2014

Pre-Calc/Trig...
you know that if the product is zero, one of the factors must be zero. SO, you have x-3 = 0 or x+2 = 0 The solutions are therefore x = -2 or x = 3. I assume you can now pick the solution with the lower value. Don't forget your algebra I, now that you're taking pre-calc!
October 16, 2014

Math
cosθ = -1/2 solutions in QII and QIII
October 16, 2014

Trigonometry
remember your double-angle formula tan2A = 2tanA/(1-tan^2 A) so, 2tanA/(1-tan^2 A) - 2tanA = -1 2tanA * tan^2 A = tan^2 A - 1 2tan^3 A - tan^2 A + 1 = 0 Hmmm. Nasty. You need to solve 2x^3 - x^2 + 1 = 0 and then take the arctan of whatever solution you find.
October 16, 2014

math
Since B+D-(B&D) = 320, 300 + D - 280 = 320 D = 300 300-280 = 20 buy only DVDs. Or, you can reason that if 300 bought Blu-ray, and 280 of those also bought DVD, then only 20 bought just Blu-ray. So, That means that the remaining 20 bought only DVDs
October 16, 2014

Advanced math
since 1,1,1,1,1... has its function ∞ ∑x^n = 1/(1-x) n=0 take the derivative ∑nx^(n-1) = 1/(1-x)^2 now replace n-1 with n and you have ∑(n+1)x^n = 1/(1-x)^2 generates 1,2,3,4,5,...
October 16, 2014

Math
well, you know the solutions will all be in QI and QIV and you know cosθ = 1/2
October 16, 2014

Advanced math
Take a look here: http://math.stackexchange.com/questions/54961/the-number-of-partitions-of-n-into-distinct-parts-equals-the-number-of-partiti and I think you will see how to build the proof you want.
October 16, 2014

Programming
print "mileage at start" read milesout print "mileage at end" read milesin print "liters consumed" read fuel rate = (milesin-milesout)/fuel print "fuel consumtion rate: ",rate," miles/liter" Now go code it up and adjust the ...
October 16, 2014

Math
check the ratio of successive terms. If it's constant, you have a GP (4x-2)/2x =?= (6x-4)/(4x-2) (2x+2)/(x+1) =?= (5x+1)/(2x+2) Looks like neither to me.
October 15, 2014

math
3√45x-√27x+17√3x-9√125x^3 3*3√5x - 3√3x+17√3x-9*5x√5x -36√5x + 14√3x or, if you will, 2√x (7√3-18√5)
October 15, 2014

8th grade
If cost = revenue for x cameras, then 2050+7x = 17x x=205 Assuming you mean 50 more than the break-even number, then since profit = revenue - cost, p = 17*255 - (2050+7*255) Another way to look at it is that the profit per camera is 17-7=10 dollars. So, with zero profit at 205...
October 15, 2014

Algebra Help
since you have 2x^2, the parabola opens upward So, it must have a minimum, which occurs at x = -16/4
October 15, 2014

Math
you are correct.
October 15, 2014

Trigonometry
I'd do it like this: in QII if sinA = 12/13, cosA = -5/13 in QIV, if sinB = -7/25, cosB = 24/25 So, tanA = -12/5 tanB = -7/24 tan(A-B) = ((-12/5)-(-7/24))/(1+(-12/5)(-7/24)) = (-253/120) / (204/120) = -253/204
October 15, 2014

Math
see a similar problem at http://www.jiskha.com/display.cgi?id=1413396134
October 15, 2014

calculus
For the graph, see http://www.wolframalpha.com/input/?i=+r+%3D+2sin%5E2%CE%B8 For the area, recall that in polar coordinates, a = ∫∫ r dr dθ = ∫[0,2π] ∫[0,2sin^2θ] r dr dθ = ∫[0,2π] 1/2 r^2 dθ [[0,2sin^2θ] = &#...
October 15, 2014

algebra
You will need x lbs, where the ratio of lbs/people remains the same. That is, 3/8 = x/10 30 = 8x x = 15/4 = 3 3/4 lbs Oh, and you'll also need a larger pie pan...
October 15, 2014

Argebra 2
enough for the anticipated pies, I guess. Sure there's not something more you want to tell us? Like how many lbs it takes to make a pie? Or how many cups, or something? If you really don't know any more than this, better look online for recipes, and they'll tell ...
October 15, 2014

Pre-Calc/Trig...
x^2 (x-2)^2 shift right 2 5(x-2)^2 stretch vertically by 5 5(x-2)^2+1 shift up 1 That should help decide.
October 15, 2014

Calculus problem (PLEASE HELP!!)
try multiplying top and bottom by x^0.3 (2x^0.3+4)/(x^0.3+1) Now you have a nice simple limit of 4/1 As x gets big, x^-0.3 vanishes, and the limit is 2/1
October 15, 2014

Map to sacle
well, if it were a scale of 1:2, it'd be 1/2 as big, right? So, you can see it will be 420/8000 m Now I'd suggest you convert that to cm for easier visulatization.
October 15, 2014

Calculus (Need help)
for f to be continuous, all three definitions must be equal at x=1. Since f is defined at x=1 in three different ways, we need -3a+4b = a-2b-1 a-2b-1 = 3-b+a So just solve those for a and b
October 15, 2014

math
Since you mention the length of the car and truck, I assume that you want the rear of the car to pass the front of the truck. So, the rear of the car is 3+10+10=23 m from the front of the truck. At a relative speed of 50 km/hr, that will take 23m/(50km/hr * 1000m/km) = 23/...
October 15, 2014

math
35 in to the square root of 2 ? Do you mean 35 in^2 If so, that's the power 2, not to the √2 Anyway, that's not enough information. Even if you restrict the rectangle to integer dimensions, it could be 1x35 - perimeter=72 5x7 - perimeter=24
October 15, 2014

Geometry
I guess C is the midpoint of AD. if so, then 5x-8 = 16-3x x = 3 Now you can find the lengths. If not, then you need to provide more details.
October 14, 2014

math
1/k + 1/7 = 1/4 Now just solve for k.
October 14, 2014

Geometry
Many people use m<A to mean "measure of angle A" Also <= or >= for less/greater than or equal
October 14, 2014

Geometry
interior is 180-x # sides is 360/x
October 14, 2014

Pre-Calc/Trig...
nope. No shapes get deformed or warped, or scaled. The whole rigid system is just moved upward.
October 14, 2014

Math
A is in QII, so cosA = -5/13 B is in QIV, so cosB = 24/25 Now, you have cos(A-B) = cosAcosB + sinAsinB ...
October 14, 2014

Chemsitry
How many grams of ice at -24.3∘C can be completely converted to liquid at 23.9∘C if the available heat for this process is 4.82×103kJ ? For ice, use a specific heat of 2.01J/(g⋅∘C) and ΔHfus=6.01kJ/mol.
October 14, 2014

Foundations and Pre-Calculus Math 10
v = 1/3 pi r^2 h so, pi/3 r^2 (3) = 30 r^2 = 30/pi r = ...
October 14, 2014

Pre-Calc/Trig...
both correct
October 14, 2014

Perimeter and Area
did you plot the points? The first one is clearly a square. So, now what is your choice? The second, assuming no typos, has duplicate points, so it is just a short vertical line.
October 14, 2014

math
Since the vertex is set at (0,0), you have a parabola y = ax^2 where y(200) = 100 a*40000 = 100 a = 1/400 y = 1/400 x^2
October 14, 2014

Math
1 kg = 1000g 603kg = 603*1000 g
October 14, 2014

Math
clearly a cube with side equal to the diameter of the sphere. So, since for a sphere, v = pi/6 d^3, just plug in your numbers and solve for d.
October 14, 2014

Math 116
since a=lw, your new area is (1.1l)(0.9w) = 0.99 lw So the area has decreased by 1%
October 14, 2014

Math 130
sure you can find the desired measures. Just consult your text for the relevant formulas and examples.
October 14, 2014

Math
Extend the sides to meet at point E. Since each exterior angle is 60°, angle BCE = CBE = 60° So, now you only have to find the third angle (angle E) of triangle BCE.
October 14, 2014

c programming
wow. Things would have been have been a lot more compact if you had used an array of month days: modays[12] = [0,31,28,31,30,...] and then just adjusted the 28 as needed for the leap year.
October 14, 2014

math
1/2 < x/8 multiply by 8 on both sides: 4 < x
October 14, 2014

Algebra
If there are x 4-seaters, and y 10-seaters, then x+y <= 52 4x + 10y >= 280 see the solution set at http://www.wolframalpha.com/input/?i=solve+x%2By+%3C%3D+52%2C+4x+%2B+10y+%3E%3D+280%2C+x%3E%3D0%2C+y%3E%3D0
October 13, 2014

math
since each equation is a straight line, each has exactly one solution. Think on it. A solution is where the graph intersects the x-axis. Two distinct lines intersect in exactly one point, unless they are parallel.
October 13, 2014

pre-calculus
revenue is room-charge * #rooms, so R(x) = (700+14x)(550-7x) That's just a parabola, and you can easily find its vertex.
October 13, 2014

Algebra
well, duh: 15 + .5x = 25 + .25x Now just solve for x...
October 13, 2014

Math
well, you have the formula: v = (3+2i)(4-i) = 14+5i
October 13, 2014

Algebra
Start from 110 feet away, a person on a bicycle rides toward a checkpoint a nd then passes it. The rider is traveling at a constant of 30m feet per second. The distance between the bicycle and the checkpoint is given by the equation d=(110-30t). At what times is the bike 40 ...
October 13, 2014

Algebra 2
If we call the equations #1,2,3 then subtract #1 from #2 and #3 from #3 to get 96a + 8b = 2 84a + 6b = 0 So, 6b = -84a, meaning 8b = -112a So, 96a - 112a = 2 -16a = 2 a = -1/8 now use that to get b = 7/4 c = 7 It would have been nice for you to have shown your work. Oh well, ...
October 13, 2014

College Physics
Since all her KE is converted to PE, 1/2 mv^2 = mgh so, 1/2 * 39.7^2 = 9.81h Note that the angle of incline makes no difference.
October 13, 2014

Algebra help
If you mean to say f(x) = 5x-1, then you are correct.
October 13, 2014

Math
as was already posted, 2cos^2 θ
October 13, 2014

Intro to Programming PT1420
nothing - there is a syntax error.
October 13, 2014

Math
If the intensity on Earth is x, then since Id^2 = k is constant, 9140*.387^2 = 1x As for rate of change, who says it's changing?
October 13, 2014

Math
Yes, I can.
October 13, 2014

Physics
If she has mass m, then she is part of the total mass. So 120 = (8.4+m)(1.7) Now just solve for m.
October 13, 2014

physics please help
√(4.57^2 + 4.74^2) / 5.76 = 1.14 m/s^2 I expect you can figure the direction.
October 13, 2014

vp manthata secondary school
Since v = πr^2h 42 = 5πr^2 r^2 = 42/(5π) r = √(42/(5π))
October 13, 2014

College Math
(a) a circle always gives the largest area for a given perimeter. Among rectangles, a square gives the largest area. (b) 1: p = 120/4 = 30 ft area: 7.5^2 = 56.25 2: c = 120/5 = 24 area: = 45.8 So, the expensive fencing reduces the circular area for planting.
October 13, 2014

MATH 101
15x^2(2x + 3) + 41x(2x + 3) + 28(2x + 3) (15x^2+41x+28)(2x+3) (3x+4)(5x+7)(2x+3)
October 13, 2014

MATH 101
40(30+41t+7t^2) 40(5+t)(6+7t)
October 13, 2014

math
(10+4)(6+4)-(10)(6)
October 13, 2014

Math
(4/5)(m-m/12) = 704 (4/5)(11/12)m = 704 11/15 m = 704 m = 704 * 15/11 m = 960
October 13, 2014

Math
After taxes, a $1 items sells for $1.085 So, the items sold account for all the extra money: (1065.95-122.00)/1.085 = 870 That's how many items were sold.
October 13, 2014

Math-Urgent help please.
4/52 * 4/51 = 0.00603 so, knowing that, choose 2
October 13, 2014

Kennedy king
(1+r)^10 = 2.0 1+r = 2.0^0.1 r = 2.0^0.1 - 1 So, to grow by a factor of 1.5, will take (1+r)^t = 1.5 2^.1t = 1.5 .1t = log1.5/log2 t = 10(log1.5/log2) = 5.85 years Depending on when interest is posted, it could take up to 6 years to see the $15K
October 12, 2014

English
Thank you
October 12, 2014

English
Jack London's works did not enjoy popularity until after his death. a- true b- false My answer is false
October 12, 2014

English
No mam just the way I wrote it. Could they be talking about gold from Alaska?
October 12, 2014

English
I agree but that is the way the homework question was stated.
October 12, 2014

English
How did gold get to California? a- dog sled b- steamship c- by airplane My answer is steamship
October 12, 2014

English
How much gold , arriving in San Francisco, triggered the gold rush? a- 500 lbs b- 1 ton c- 2 tons My answer is 2 tons
October 12, 2014

geometry
a vertical line has equation x=h for some h. You have the point (5,6), so x=5 Similarly for horizontal lines and y.
October 12, 2014

Calculus
since h = 2r, r = h/2 v = pi/3 r^2h = pi/12 h^3 So, dv/dt = pi/4 h^2 dh/dt When h=6, we have 25 = 9pi dh/dt Now just do the math
October 12, 2014

math
Yeah, that's the problem when the assumptions aren't explained. Another way would be to assume the bill included the tax, so the actual meal only cost 56.25/1.075, and the tip was calculated on that basis. There'd be no reason to even mention the tax if it weren&#...
October 12, 2014

math
c'mon. You get a bill for $56.25 You tip 15%, which is 56.25 * .15 You add that to the bill, so your final amount is 56.25 + 56.15 * .15 = 56.25(1+.15)
October 12, 2014

math
Depends - do they tip on the whole bill? Most folks do. In that case, they spent $56.25 * 1.15 if the tax is included in the bill, as is usually the case.
October 12, 2014

geometry
I just did! The line AB has slope -5. So, any line parallel AB also has slope -5. The line you want is thus y-1 = -5(x+2)
October 12, 2014

geometry
a line with slope m containing (h,k) is y-k = m(x-h) Now plug in your values.
October 12, 2014

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