Thursday

September 29, 2016
Total # Posts: 44,235

**profit and loss**

.55*1.05 + .45*1.08 = 1.0635 .45*1.05 + .55*1.08 = 1.0665 so, what is the % change? The amount invested does not matter, since it is all the same.

*September 5, 2016*

**math**

let's just call 4/3 pi = k since it does not depend on r. v(2r)/v(r) = k(2r)^3/kr^3 = 8kr^3/kr^3 = 8

*September 5, 2016*

**Calculus**

come on - you did this for 2D figures back in Algebra II: x^2+4x + y^2-2y + z^2-2z = 19 x^2+4x+4 + y^2-2y+1 = z^2-2z+1 = 19+4+1+1 (x+2)^2 + (y-1)^2 + (z-1)^2 = 25

*September 4, 2016*

**Math**

since -1 <= sin(u) <= 1 e^x -> +∞ 1/∞ = 0 as x -> +∞ But, oddly enough, this only a one-sided asymptote, since e^-∞ = 0, e^x-2 -> -2 as x -> -∞ And of course, there is the vertical asymptote at x = ln(2) http://www.wolframalpha....

*September 4, 2016*

**calculus**

yeah - where f'(x) = 0 f'(x) = -10sinx + 10cos2x now just find where that is zero

*September 4, 2016*

**calculus**

Let's take this a step at a time F' = f'(xf(xf(x))) * (xf(xf(x)))' (xf(xf(x)))' = f(xf(x)) + xf'(xf(x)) f'(xf(x)) = f(x) + xf'(x) so: F'(1) = f'(1f(1f(1))) * (f(1f(1)) + f(1)+f'(1)) = f'(f(4)) * (f(4)+f(1)+f'(1)) = f'(6...

*September 4, 2016*

**calculus**

clearly there are none.

*September 4, 2016*

**Math**

put it where? 2.0*10^-7 / 8.0*10^-9 = (2.0/8.0)*10^(-7 - (-9)) = 0.333 * 10^2 100/3

*September 4, 2016*

**Math**

still no ideas of your own? Try google when you have no clue: http://math.stackexchange.com/questions/202679/sum-of-digits-and-product-of-digits-is-equal-3-digit-number

*September 4, 2016*

**Algebra**

same as always (1+(2i/n))^2 *(2/n) (1 + 2(2i/n) + (2i/n)^2) * (2/n) 1(2/n) + 2(2i/n)(2/n) + (2i/n)^2(2/n) 2/n + 8i/n^2 + 8i^2/n^3

*September 4, 2016*

**Math Algebra**

A is the same distance from (1,3) as B is. You don't need to know that the distance is √29. You just need to subtract the same values from (1,3) as were added to get to (4,-1) (1,3)+(3,-4) = (4,-1) So, you need (1,3)-(3,-4) = (-2,7)

*September 4, 2016*

**algebra**

82.4 <= f <= 659.2

*September 4, 2016*

**maths**

2(n+12) = 3/2 (2n+12)

*September 4, 2016*

**Math**

when you have no clue, try google first: https://answers.yahoo.com/question/index?qid=20090501152219AAtVxte

*September 4, 2016*

**Math**

Clearly the T can occur in any of the 3 positions.

*September 4, 2016*

**Math**

any of 18 different numbers can show on each roll. So, there are 18*18*18 different sets of 3 events

*September 4, 2016*

**Pre cal**

I assume you get this far ok: ... (x-4)(x^2+4) x^3-4x^2+4x-16 evaluate that at x = -1, and you get -1-4-4-16 = -25 That means that if f(x) = a(x^3-4x^2+4x-16) then f(-1) = -25a But, we want f(-1) = -50 so, -25a = -50 a = 2 f(x) = 2(x^3-4x^2+4x-16)

*September 4, 2016*

**Math**

wait - we doing heights or lengths? anyway, average = sum/count

*September 4, 2016*

**yuiljk**

200/50 + 1

*September 4, 2016*

**Physics**

subtract the area of the hole from that of the disc rim; then multiply by the thickness: π(128^2 - 15^2)(0.75) mm^3

*September 4, 2016*

**Math**

it will be the same as when it went up.

*September 4, 2016*

**Basic Math**

yes, it would.

*September 4, 2016*

**Computer science**

If you haven't already written your own routine, google one of your choosing. You should "zero" in on n ≈ 19.2681

*September 4, 2016*

**Physics**

work = force * distance the mass does not matter; it just affects how long it will take.

*September 4, 2016*

**MATH**

1 * 26^3 * 10^2

*September 4, 2016*

**Algebralgebrad**

no, 1+tanx is not the same as 1+tan^2x use your sum-to-product formulas: cosx-cosy = -2 sin(x+y)/2 sin(x-y)/2 sinx+siny = 2 sin(x+y)/2 cos(x-y)/2 so the quotient is just -tan(x-y)/2 the 2nd term is similar recall that (a+b)^3 = (a+b)(a^2-ab+b^2) csc2x = 1/sin2x = 1/(2sinx cosx...

*September 4, 2016*

**Math**

since 24 = 6*2^2 any multiple of 6 that does not also have 2 as a factor: 6*1=6 6*3=18 6*5=30 6*7=42 etc.

*September 4, 2016*

**algebra**

as with any cone, v = π/12 d^2 h

*September 4, 2016*

**mathematics - algebra**

well, tanθ >= 121/915, so ...

*September 4, 2016*

**Pre Calc**

http://www.wolframalpha.com/input/?i=-x%5E2%2B9x-8

*September 4, 2016*

**Math**

30*4.2 -------- 5/3

*September 4, 2016*

**math help**

y = x^2/2 y' = x so, the line through (3,9/2) with slope=3 is y - 9/2 = 3(x-3)

*September 4, 2016*

**Math**

5/20 = ...

*September 4, 2016*

**Trignometric**

2tan^2(x) + sec^2(x) = 5 - 4tan(x) 2tan^2(x) + 1+tan^2(x) = 5 - 4tan(x) 3tan^2(x) + 4tan(x) - 4 = 0 (tanx+2)(3tanx-2) = 0 Now you know tan(x) cot(a+b) = 6 (cota*cotb-1)/(cota+cotb) = 6 cota = -2, so (-2cotb-1)/(-2+cotb) = 6 -12cotb-6 = -2+cotb -4 = 13cotb cotb = -4/13 or, use ...

*September 4, 2016*

**algebra**

how many o's? how many total letters?

*September 4, 2016*

**Math**

south: 120 cos46° west: 120 sin46°

*September 4, 2016*

**Algebra**

y = k/x 2 = k/6 ...

*September 4, 2016*

**Math**

I'll use x for ease of typing each turkey cost x.xx/72 72*x.xx = x67.9x start listing multiples of 72 that end in 9x: 72*11 = 792 72*18 = 1296 72*36 = 2592 Check to see which works out

*September 3, 2016*

**MATH**

x+y+z = x*y*z 1+2+3 = 1*2*3 ...

*September 3, 2016*

**physics (Simple harmonic motion)**

assuming t is in seconds, I don't see how to get 37.963m http://www.wolframalpha.com/input/?i=0.142sin(2t%2B0.19)+for+0%3C%3Dt%3C%3D210 unless t1 is not zero

*September 3, 2016*

**Calculus**

of course, the range is just the same as the range of 2sin(x)+3: [1,5] http://www.wolframalpha.com/input/?i=2sin(sqrt(3x-1))+%2B+3

*September 3, 2016*

**Calculus**

no idea. Just take it step by step. domain of √x is x>=0 so, the domain of √(3x-1) is 3x-1 >= 0, or x >= 1/3 the domain of sin(x) is all reals, so the domain of sin(√(3x-1)) is the domain of √(3x-1), or x >= 1/3

*September 3, 2016*

**Calculus**

that's a start. Now consider that 4 = 2^2 8 = 2^3 So, log_4(8) = (1/2)log_2(8) = 3/2 log_8(16) = (1/4)log_2(16) = 4/3 (3/2)/(4/3) = 9/8

*September 3, 2016*

**Calculus**

e^(1+2lnx) = e^1 * e^2lnx = e * (e^lnx)^2 = e * x^2 That should help some Tsk Tsk, Damon

*September 3, 2016*

**math**

The latus rectum's length is 2 times the distance from the focus to the directrix. Now recall the point-to-line distance formula, and you get |3*1-4*1+7|/√(1^2+1^2)

*September 3, 2016*

**Math**

as you know, the domain of sin(x) is (-∞,∞) The domain of √x x>=0 so, the domain of √(3x-1) is 3x-1 >= 0, or x >= 1/3 so, can you sort that out?

*September 3, 2016*

**Math**

well, geez! How many factors of 16 are there between 6 and 15?

*September 3, 2016*

**math**

if the denominator has any factors other than 2 or 5, it will make a repeating decimal.

*September 3, 2016*

**math**

you need to plot these values on the number line. You can see that the leftmost point is -3 1/4 and the rightmost is 2 1/3 Thus, the greatest difference is between them: 2 1/3 - (-3 1/4) = 5.583 If "greatest" product means its algebraic value, then any positive ...

*September 3, 2016*

**Math**

what a lot of similar problems. I''ll do this one, and maybe you can use it to solve the others. If not, show where you get stuck. 1/3 + 1/4 + 3/8 = 8/24 + 6/24 + 9/24 = 23/24 So, only 1/24 is left, meaning that if he started with x hectares, x/24 = 9 x = 216

*September 3, 2016*

**algebra 1**

correct, since both values are rational

*September 3, 2016*

**Maths**

if the plane turns south at point P, then if you set AP along the +x axis, then the angle θ=PAB is tanθ = -80/100 θ = -39° That's E39°S or a bearing of 129°

*September 3, 2016*

**maths**

Since vertex O is common to both triangles OCD and OAB, you have SAS to show that the two triangles are congruent, making CD and AB congruent.

*September 3, 2016*

**Maths**

m + 4(m-20) = 330

*September 3, 2016*

**Math**

Hmm. I get x = 2y 3.50x + 5.25y = 1,225.00 Having twice as many dogs as burgers has nothing to do with their prices.

*September 3, 2016*

**Math**

Draw a diagram. It should be clear that when the water has depth y ft, the cross-section of water has area y^2/2 ft^2. So, the volume v = 20y^2 dv/dt = 40y dy/dt when y = 6 in = 1/2 ft, 3 = 40(1/2) dy/dt now just solve for fy/dt, the rate the depth is changing. That is, how ...

*September 2, 2016*

**English**

#1 is ok, but simply removing the "that" is awkward. Note that it humorously ambiguous: "died suddenly," or "suddenly suprised me"? #2 is syntactically correct, but an unusual usage. I'd not remove the "that" #3 I'd not use "...

*September 2, 2016*

**help please!**

consider the parameter t such that when t=0 you are at the first point, and when t=1 you have moved to the 2nd point. For x, the would be x = x1 + (x2-x1)t x = -9 + (2-(-9))t and similarly for y and z.

*September 2, 2016*

**jccc**

you gotta work on your copy/paste stuff

*September 2, 2016*

**Electricity and Magnetism**

what's the trouble? Just plug into the formula: F = keq1q2/r^2

*September 2, 2016*

**Algebra**

just substitute x-3 for each x: h(x-3) = (x-3)^3 + 4(x-3)^2 If you want, expand that into the usual polynomial form.

*September 2, 2016*

**science**

trick question carbon filament bulb?

*September 2, 2016*

**science**

pooop

*September 2, 2016*

**pre calc!!!**

the line through (1,-1,2) is (x-1)/a = (y+1)/b = (z-2)/c and <a,b,c> is the desired direction vector. Note that your parametric equations can be converted to symmetric by eliminating t: (x+7)/-4 = (y+5)/-7 = (z-2)/-4 That should be a large enough clue, no?

*September 2, 2016*

**Algebra**

x^3-x^2+x-1 = (x^2+1)(x-1) x^2-1 = (x+1)(x-1) So, the LCM is (x^2+1)(x-1)(x+1) = (x^2+1)(x^2-1) = x^4-1

*September 2, 2016*

**Algebra**

just make the substitution: h(a-4) = 2^(a-4)+1 = 2^a/16 + 1 or, if you were careless with parentheses, h(a-4) = 2^(a-4+1) = 2^(a-3) = 2^a/8

*September 2, 2016*

**Algebra**

or, -3 * 4*4^(4n) = -12 * 4^(4n) = -12 * 256^n

*September 2, 2016*

**Pre-algebra**

1/2 * 2/6

*September 2, 2016*

**Math**

much better

*September 2, 2016*

**Math**

Nope. |-10| = +10

*September 2, 2016*

**Math**

your example is simply volume. Look at the units. You have m^3 + m^2 * m but m^2 * m = m^3 so both terms are volume

*September 2, 2016*

**Math**

If the length unit is, say, ft, then length is in ft area is in ft^2 volume is in ft^3 So, see what the power of the unit is to determine the quantity being measured.

*September 2, 2016*

**science ( physics )**

The relative speed of A,B and C is x+10 It takes C 1 minute at (x+10)km/hr to cover the 0.5km distance. So, (x+10)(1/60) = 1/2 x = 30 km/hr Or, let the rear car be at point 0, and the front car at 0.5. The rear car is moving in the + direction, and C is moving in the - ...

*September 2, 2016*

**Math Algebra**

If the number is xy (digits are x and y), then 10y+x = 10x+y + 36 x+y = 10 Now just find x and y

*September 2, 2016*

**math**

recall that sin(180-x) = sin(x) cos(180-x) = -cos(x) Using those two facts, you can replace each angle by its supplement. Now, if you want to get fancy, sin(90+x) = cos(x) cos(90+x) = -sin(x) As Reiny suggested, start by drawing triangles in the "standard position." ...

*September 2, 2016*

**Chemistry**

Balance the equation. how many moles in 12.1g H2 ? You'll need twice that many moles of HCl So, how much 27% solution will have that many moles?

*September 2, 2016*

**Algebra 1**

5.99x > 5525 + 2.50x

*September 1, 2016*

**algebra**

multiply both sides by 4 If two quantities are equal multiplying them by the same value will retain their equality.

*September 1, 2016*

**integrated science**

time = distance/speed Plug and chug

*September 1, 2016*

**Calculus**

(3^x)(e^x) = (3e)^x recall that d/dx a^x = lna a^x that help?

*September 1, 2016*

**Math**

what are all the dots? Do they count for something? so we are just to use a single symbol twice, once for each blank?

*September 1, 2016*

**Algebra**

x = 3x+6

*September 1, 2016*

**Math**

v = x(3x+2)(2x-4) Now just expand that out

*September 1, 2016*

**physics**

s = 1/2 at^2, so 1/2 a * 4.54^2 = 8.1 Now use that to figure how far it goes in the next second. v = a*t s = v*1 + 1/2 a * 1^2

*September 1, 2016*

**science help pls pls**

google planetary orbit period You will find lots of explanations, with the formula. I cannot believe that this question was asked of you without providing the formula, either in class or in the text. I also cannot believe that you expect someone to provide it for you.

*September 1, 2016*

**science help pls pls**

Just plug these numbers into your formula for orbital periods and subtract.

*September 1, 2016*

**math**

first place in standard form: x^2/8 + y^2/3 = 1 Since a^2 = 8 is greater than b^2 = 3, the major axis is horizontal. So, we have a^2 = 8 b^2 = 3 c^2 = a^2-b^2 = 5 Now just read off the info you want: center: (0,0) foci: (±c,0) vertices: (±a,0)

*September 1, 2016*

**Math**

consider 8^12 = 8*8*8...*8 12 times 8*9 = 8*8*8...*8 9 times nine of those factors cancel out, leaving 3 in the top, or 8^3 This is why x^m / x^n = x^(m-n) since n of the factors cancel out when reducing the fraction.

*September 1, 2016*

**Discrete Math Proof Exercise**

first, you need to show that only even+odd = odd even+even = 2m+2n = 2(m+n) = even odd+odd = 2m+1 + 2n+1 = 2m+2n+2 = even even+odd = 2m + 2n+1 = 2(m+n)+1 is odd so, if 3n^2+5 is odd, 3n^2 is even Since 3 is odd, n^2 must be even, which means that n is even, since odd*odd = (2m...

*September 1, 2016*

**Calculus**

Let M = ∫ e^(2x) cos3x dx u = cos3x du = -3sin3x dx dv = e^(2x) dx v = 1/2 e^(2x) M = uv - ∫v du M = 1/2 e^(2x) cos3x + (3/2)∫e^(2x) sin3x dx Now consider ∫e^(2x) sin3x dx u = sin3x du = 3cos3x dx dv = e^(2x) dx v = 1/2 e^(2x) ∫e^(2x) sin3x dx = 1...

*September 1, 2016*

**MATH**

3/5 * 3/4 = 9/20 so, if the full amount is x, then 9/20 x = 360 x = 360 * 20/9 5/8 of x is thus (5/8)(360)(20/9) = ?

*September 1, 2016*

**Math**

slope = 4, so the point-slope form of a line is y+1 = 4(x+5) massage that into whichever other form you desire

*September 1, 2016*

**Mathematics**

since the distance is the same, rate*time is constant. So, you want m minutes where 36m = 15*60

*September 1, 2016*

**algebra,geography**

see related questions below.

*September 1, 2016*

**Math asap**

and you are wrong. -3 < 2

*September 1, 2016*

**Math asap**

see related questions below. I know I've seen this answered at least once for you.

*September 1, 2016*

**Math**

still 3, right?

*September 1, 2016*

**Math**

15500

*September 1, 2016*

**Geometry**

no idea what you are saying: M 6 + 16 + z -1 and 14 ???!?!?!?

*September 1, 2016*