Friday

May 22, 2015

May 22, 2015

Total # Posts: 31,325

**maths**

tan7θ tan3θ = 1 express in terms of sin and cos: sin7θ sin3θ = cos3θ cos7θ cos3θ cos7θ - sin7θ sin3θ = 0 Things should be starting to look familiar now . . .
*May 22, 2015*

**math**

experimental loaded dice!
*May 22, 2015*

**math**

the vertex of ax^2+bx+c is at x = -b/2a In this case, that is 750/50 = 15, not 9. v(15) = 4375
*May 22, 2015*

**math**

well, that would just be the difference between the two temperatures. How do you find the difference between two numbers? For example, how much bigger is 100 that 20?
*May 21, 2015*

**Physics**

I see a lot of verbage, but nothing related to actually solving this problem. Draw a diagram of the vectors involved. Clearly, sin α = 10/80, so α = 7.18° The speed at touchdown will be 80 cosα = 79.37 mi/hr
*May 21, 2015*

**Physics**

nope: C 1/20 = 1/8 + 1/x x = -13.3
*May 21, 2015*

**Math**

stupid cursing filters! 8/2 = 4 cages of c**katiels 32/10=3.2, so 4 cages of parakeets 28/10=2.8, so 3 cages of finches
*May 21, 2015*

**Math**

ooops. negative multiplication changes direction: -2x < 9 x > 9/-2 x > -4.5
*May 21, 2015*

**math**

see related questions below
*May 21, 2015*

**algebra**

original amount: x apples Becky gets (x+1)/2, leaving Joy (x-1)/2 Gayle gets (x+1)/4, leaving Joy (x-3)/4 Bonnie gets (x+1)/8, leaving 1 left over x - (x+1)/2 - (x+1)/4 - (x+1)/8 = 1 x = 15 or, working backwards, there were ((1*2+1)*2+1)*2+1 = 15 apples to start
*May 21, 2015*

**MATH PRACTICE**

if you look at the coordinates, you just have a right triangle, with legs of length 4 and 7. So, figure the hypotenuse and add 'em up. I get something close to 19.
*May 21, 2015*

**Algebra**

√(1/5) - √5 1/√5 - √5 (1 - √5√5)/√5 (1 - 5)/√5 -4/√5
*May 21, 2015*

**Zoneton**

formatting. Should have been -2x < 9 x > ??? Swap sides to get -9 < 2x -9/2 < x or, x > -9/2
*May 21, 2015*

**Math.**

Clearly you need to review your shapes and their volumes. v = pi/3 r^2 h r=12 and h=10, so v = 3.14/3 * 12^2 * 10 = 1507.2 in^3
*May 21, 2015*

**English**

not necessarily. #2 is just motion #1 also implies intent -- to eat you.
*May 21, 2015*

**Maths**

well, which of them tends to oscillate between a max and a min on a regular (say, daily) basis?
*May 21, 2015*

**math**

mean
*May 21, 2015*

**Calculus and quadratic equations**

The data points are: (0,10000), (3,7075), (6,6400), (9,5275) The instructions say: If the last digit of your Student ID No. is an integer power of 2, then you are to use the initial investment value and data from 3 weeks and 6 weeks to work out the model. So, now you know ...
*May 20, 2015*

**math**

looks like 6 to me there are 3 ways to make the first move. Then from the new corner, there are 2 ways to continue. Then there is a single last move.
*May 20, 2015*

**physics**

the horizontal speed is 17.32 m/s So, the package falls for 750/17.32 = 43.30 seconds So, you need h where h + 10.0t - 4.9t^2 = 0 and t = 43.3 Now you can carry on with the other parts,
*May 20, 2015*

**English**

The expression is "have it easy." similarly expressions: Some like it hot. I can't get it right. Using "easily" would indicate the having, rather than what is being had. (Also, I've never heard anyone say it!)
*May 20, 2015*

**Geometry**

I'd say the distance formula, given the definition of a parabola.
*May 20, 2015*

**Trig - My Bad**

I messed up on my sign (QII) So, Reiny, how did you get 5/12? That was -tanØ
*May 20, 2015*

**Trig**

Not sure I like your values: sin2θ = 2sinθcosθ = 2(-5/13)(-12/13) = 120/169 cos2θ = 2cos^2θ-1 = 2(144/169)-1 = 119/169 tan2θ = sin2θ/cos2θ = 120/119
*May 20, 2015*

**Trig**

since π < θ < 3π/2 (QIII), sinθ = -5/13 tanθ = 5/12 Now just plug those into your double-angle formulae.
*May 20, 2015*

**PHYSICS**

so, what are your calculations? Maybe we can figure out what's wrong.
*May 20, 2015*

**L A/The Giver**

I agree with #1 Have you read the other two books in the series? Good story.
*May 20, 2015*

**math**

If the loan is for 62 days, then you want just 62/360 of the 15% for interest, since it's 15% for a whole year. (assuming the 360-day year)
*May 20, 2015*

**math**

I assume you want just the region in QI, since otherwise the axis of rotation is inside part of the region. So, we want the area whose vertices are (0,0), (0,1) and (π/2,π/2) Around the x-axis, we have, using discs, v = ∫[0,π/2] π ((x+cosx)^2 - x^2) ...
*May 20, 2015*

**help**

x + 3x = 20 . . .
*May 20, 2015*

**physics**

No.
*May 20, 2015*

**math**

to find the # of children's tickets, you just solve 35(2c) + 20c = 1890 then double that for the adults.
*May 20, 2015*

**Good call, Reiny**

Yes, I neglected to mention excluded values. One cannot gloss over stuff like that. My bad.
*May 20, 2015*

**algebra**

x/(6x-x^2) = x / x(6-x) = 1/(6-x) (x^2 - 3x - 18) / (x + 3) = (x-5)(x+3)/(x+3) = x-5 (k+3)/(4k-2) * (12k^2+2k-4) = (k+3)/(2(2k-1)) * 2(2k-1)(3k+2) = (k+3)/(3k+2)
*May 20, 2015*

**math**

if there's a 20% discount, it sells for 80% of its original price. so, 0.80 p = 126.40
*May 20, 2015*

**math**

well, geez, just check your answer 11 dimes and 2 nickels does indeed add up to $1.20
*May 20, 2015*

**math**

add up the coins: n+d = 13 add up the values: 5n+10d = 120 Now just solve for n and d.
*May 20, 2015*

**Algebra**

(8m^7 - 10m^5) / 2m^3 = 8m^7/2m^3 - 10m^5/2m^3 = 4m^4 - 5m^2 -2/(x+3) - 4/(x-5) = [-2(x-5) - 4(x+3)] / (x+3)(x-5) . . . 7/(x-3) + 3/(x-5) = [7(x-5) + 3(x-3)] / (x+5)(x-3) . . . -1/(x-9) - -2/(x+7) = [-(x+7) + 2(x-9)] / (x-9)(x+7) . . .
*May 20, 2015*

**Trig**

correct.
*May 20, 2015*

**algebra**

yes, it appears to be an exercise in the distributive property. Do you have a question? I expect you need to use the property to get rid of the parentheses and then solve for the variables. What do you get?
*May 20, 2015*

**Statistics**

so, at 5% per period, after 6 periods, the account will have 2000*1.05^6 + 2000*1.05^5 + ... + 2000 = 2000(1.05^7 - 1)/0.05 = 16284.02
*May 20, 2015*

**geometry**

well, v = 1/3 πr^2 h so, unless you know something about the height, there's no way to pin down the radius. All you know for sure is that r^3 h = 960/π Maybe you can fix things and then solve for r. Please don't just come back and say h=5, so what's r? ...
*May 20, 2015*

**CSIR General Aptitude**

Just subtract the starting position from the ending position to get the distance traveled...
*May 20, 2015*

**pre-algebra**

9z+8+3(2-4z)-9=-40 9z+8+6-12z-9 = -40 -3z+5 = -40 -3z = -45 z = 15
*May 20, 2015*

**math**

I assume you meant exactly 2 standard deviations above the mean So, 2 std's = 8, making the mean 85-8 = 77
*May 20, 2015*

**Maths**

so, what's wrong with that as an answer? That's what I get, too. http://www.wolframalpha.com/input/?i=1%2F%281%2F%281%2B2i%29+%2B+1%2F%282%2B5i%29%29
*May 20, 2015*

**Math Check Answers Quickly Please**

both are correct.
*May 20, 2015*

**math**

If the base is a n-gon, then the base has n sides and n vertices. So, clearly the pyramid has n lateral faces and edges, no?
*May 20, 2015*

**Maths**

depends on the tools you have learned. Most easily, use a calculator. figure 18*3.14159/5.86 and then hit the sin button. Make sure you are in radian mode.
*May 20, 2015*

**math**

have you no calculator? If not, you can just enter that text into the google search box, and it will give you the result.
*May 20, 2015*

**science**

check the label to see the expected delay.
*May 20, 2015*

**Math**

5m+13
*May 19, 2015*

**algebra2**

That file exists only on your computer. No way for us to open it. Best suggestion: review the properties and work it out. Next best: tell us the question for some help.
*May 19, 2015*

**Math**

you can find the distance PQ using the law of cosines: x^2 = 10^2 + 6^2 - 2(10)(6)cos137° x = 14.959 for the bearing, locate P and Q in rectangular coordinates and then the bearing is 90-arctan(y/x) where x and y are the corresponding displacements from Q to P.
*May 19, 2015*

**Algebra 2 Honors**

you can get that without worrying about k. since r = kst, r/st = k and is constant. So, you need s in 140/(-5*20) = 7/(2.5s) s = -2 as you calculated
*May 19, 2015*

**algebra**

-1/(x-9) - -2/(x+7) -1(x+7) - (-2)(x-9) ------------------------- (x-9)(x+7) (-x-7+2x-18) / (x-9)(x+7) (x-25) / (x-9)(x+7)
*May 19, 2015*

**algebra**

a/b/c (a/b)/c = a/(bc) So just plug in your values and reduce.
*May 19, 2015*

**Calculus**

1. I get = π[(1/4)y^2 + y] from -2 to 1 = π((1/4+1)-(1-2)) = 9π/4 2. I get 9π/4 also making the total volume 9π/2
*May 19, 2015*

**Calculus**

suppose ∫ f(x) dx = F(x) Then ∫[0,8] f(x) dx = F(8)-F(0) = 4 ∫[0,2] f(4x) dx = ∫[0,2] 1/4 f(4x) d(4x) = 1/4(F(8)-F(0)) = 1 check: ∫[0,8] x^2 dx = 512/3 ∫[0,2] (4x)^2 dx = 16(8/3) = 128/3
*May 19, 2015*

**math please help**

the perimeter is just the sum of all the sides. So, for the large triangle, p = 4x+2 + 7x+7 + 5x-4 = 16x+5 Now do the same for the smaller triangle. For (B), just subtract one expression from the other.
*May 19, 2015*

**Calculus**

how about |x^2-cosx| or, 2*integral from 0 to 2, since both cosx and x^2 are even?
*May 19, 2015*

**Calculas**

the volume of a disc of thickness k is pi r^2 k If the radius is y, it means you are rotating around the x-axis, so the volume of each disc is pi y^2 dx If rotating around the y-axis, each disc's radius is x, so the volume is pi x^2 dy Try drawing a diagram, guys. As you ...
*May 19, 2015*

**Calculas**

pi y^2 is used when rotating around the x-axis.
*May 19, 2015*

**Calculas**

if you use discs, they have holes. Shells are just like nested cylinders, so there are no holes. Using discs (washers), the calculation is more complex, since the lower portion is bounded by the y-axis (solid discs), and the upper portion is bounded by the two curves (washers ...
*May 19, 2015*

**Calculus**

The curves intersect at (±√3,4) So, using the area in the first quadrant, we have, using shells, v = ∫[0,√3] 2πrh dx where r=x and h=(x^2+1)-(2x^2-2)=(3-x^2) v = 2π∫[0,√3] x(3-x^2) dx = 9π/2 Looks more like a bowl than a vase...
*May 19, 2015*

**Calculus**

because f(-x) = -f(x) There is equal area above and below the x-axis.
*May 19, 2015*

**Quadratic Functions and Calculus**

Holy crap! Have you done anything on this? Have you determined the three data points to use? Have you decided what to do using the ID number? Come back with some input, ok?
*May 19, 2015*

**Quadratic Functions**

Not sure what BiQuad is, but if you want to fit a parabola through those three points, you have, assuming that v(t) = at^2 + bt + c, 0a+0b+c = 10000 9a+3b+c = 2025 36a+6b+c = 6400 Somehow I suspect what you really wanted was v(3) = 1000-2025 = 7975, since most stocks don't...
*May 19, 2015*

**math**

well, shoot. Which is bigger: a ft^3 or a yd^3?
*May 19, 2015*

**math please help**

they are the same. It shows why 11^0 = 1 or why x^0 = 1 for any value of x. (except x=0)
*May 19, 2015*

**math help please!!**

3^3/3^6 = 3*3*3 ----------------- 3*3*3*3*3*3 Now you can see that three 3's cancel out in top and bottom, so you are left with 1/(3*3*3) = 1/27 This shows why x^n / x^m = x^(n-m)
*May 19, 2015*

**Math**

can you try that again in English?
*May 19, 2015*

**Math**

the cars are 360/16 = 22.5° apart. car 16 is 3 positions from car 13. So, a rotation of 67.5° will move car 16 to car 13's position.
*May 18, 2015*

**geometry**

in a triangle, angles are opposite sides. Two angles cannot be opposite each other. Using the tan function, the hypotenuse is not used. If the base 12 is opposite the 71° angle, then 12/d = sin 71° 12/c = tan 71° Better review your trig function definitions.
*May 18, 2015*

**Math**

you have a rectangle that is 100x(40+20) and a circle that has diameter 40+20=60 so, just add those two areas. If the area inside the circular ends but outside the rectangle does not count, then you have to subtract off the smaller circle of diameter 40.
*May 18, 2015*

**Math**

a^2 = 6 b^2 = 5 c^2 = a^2+b^2
*May 18, 2015*

**Math**

you want x minutes, where 12+.05(x-500) = 10+.04(x-300) x = 1100
*May 18, 2015*

**math**

each interval has width 2, so the midpoints are at 1,3,5,7,9
*May 18, 2015*

**math**

16-x^2 is concave down, so you want to use the right endpoints. Each interval has width 1, so you just have 2(f(1)+f(2)+f(3)) = 2(15+12+7) = 68 There are several good online Riemann Sum calculators. You can use them to verify your work.
*May 18, 2015*

**math**

see related questions below
*May 18, 2015*

**math**

just plug in the values for n: t1 = 7 t2 = 2t1-3(2) = 2(7)-3(2) = 8 t3 = 2(8)-3(3) = 7 ...
*May 18, 2015*

**math**

so, did you use the formula?
*May 18, 2015*

**algebra 2 and trig**

how many std's away is the 2.5% boundary? The mean is at (78+92)/2 = 85
*May 18, 2015*

**Calculus**

Assuming x is not zero, the fractions are zero when the numerators are zero. So, f'=0 when 8x+1 = 0, or x = -1/8 f"=0 when 4x-1 = 0, or x = 1/4
*May 18, 2015*

**Algebra 2**

revenue for x hats is y=15x cost is y=0.4(x-150)^2+9000 So, you want x when 15x >= 0.4(x-150)^2+9000 x >= 262.5 so, at least 263 hats
*May 18, 2015*

**Math**

if the chord length is 2x, then half the chord subtends half the angle: x/200 = sin 34°
*May 18, 2015*

**please help math**

it is that.
*May 18, 2015*

**math please help**

after n years, its value is 400(1.07)^n
*May 18, 2015*

**Calculus**

it reverses direction when its velocity changes sign. That is, when v(t) = 0. So, find t when v(t) = s'(t) = 3t^2 - 18t + 24 = 0 then plug that value into s(t) and a(t)
*May 18, 2015*

**Math**

he used 15.75-10.5 = 5.25 gallons of paint in 1.5 hours. That is 3.5 gal/hr Thus, using the point-slope form of the line, if y is the amount of paint left at x hours after 12:00, then y-10.5 = -3.5(x-2) So, find y when x=0. Or, knowing that he used 3.5 gal/hr, and knowing that...
*May 18, 2015*

**math please**

when dividing numbers expressed as powers, you subtract the exponents. Think about it 10^7/10^3 = 10*10*10*10*10*10*10 --------------------------- 10*10*10 Three of the factors cancel, and you are left with 7-3 = 4 multiples of 10. That is 10^(7-3) = 10^4 So, you want (C)
*May 18, 2015*

**Math**

216 = 6*6^2 96 = 6*4^2 so, you wind up with 6√6t + 4√6t = 10√6t = √600t
*May 18, 2015*

**Algebra**

a = w(w+4) . . .
*May 18, 2015*

**MATH if work is correct**

78125 = -5^7 So, starting with 5^-2, the 10th term is -5^7 Note that the 3rd term is 1=5^0. So, you have to multiply by -5 another 7 times to get to -5^7.
*May 18, 2015*

**Math**

the full volume is 60*60*45 2/3 of that is still empty. So, divide that volume by 6 L/min (6000 cm^3/min) to get the time needed.
*May 18, 2015*

**Math**

In how many different orders can you read 4 books
*May 18, 2015*

**science**

a body of mass 5kg is thrown to a height of 100m.what is its potential energy at the maximum height.?
*May 18, 2015*

**math Help!!!!**

There are 6 ways you can draw the two marbles to include one red: RB,RY,RW,BR,YR,WR There are 4P2 = 12 ways to draw any two marbles So, P(one red) = 6/12 = 1/2
*May 18, 2015*

**math...Please help!!!!**

I think B, but the language is garbled. The SD will not change. Read up on how the SD is figured, and you should see why.
*May 18, 2015*

**Geometry**

h^2 + 7^2 = 28^2
*May 18, 2015*