Friday

May 6, 2016
Total # Posts: 40,219

**Math haha**

Or, since it is the difference of two squares, (7/2+5/6)^2 - (7/2-5/6)^2 = (7/2+5/6 + 7/2-5/6)(7/2+5/6 - 7/2-5/6) = (7)(5/3) = 35/3
*March 20, 2016*

**Math**

1 > x > 9/8 is not possible, since 1 < 9/8
*March 20, 2016*

**Math**

no idea. Start listing them. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ... Seems like kind of a dumb question.
*March 20, 2016*

**mathematics-Algebra**

just put the words into math: If the numbers are x and y, then sum: x+y difference: x-y avg of sum and difference: ((x+y)+(x-y))/2 = x diff of sum & diff: (x+y)-(x-y) = 2y product is thus 2xy=12 3x+y=11 even with no further algebra, it is easy to see that x=3 and y=2
*March 20, 2016*

**Math**

t+o=8 6t+7o=53
*March 20, 2016*

**Algebra**

8*10*L = 2080
*March 20, 2016*

**MATH**

right.
*March 20, 2016*

**Physics**

A 5kg block is being pulled on a horizontal frictionless surface. The tension in the string is 30N. What is the total work done on the block as it moves a distance of 10 meters? Thank you very much!
*March 20, 2016*

**math**

4:5
*March 20, 2016*

**math**

x = ky^3 1 = k*2^3 k = 1/8 now just crank out the answers
*March 20, 2016*

**Math - incomplete**

got to know the total number sold. All you've said is that s = 3h you still need s+h = ? Fill in that value and then solve the two equations.
*March 19, 2016*

**Calculus**

h=3r, so r = h/3 v = π/3 r^2 h = π/3 (h/3)^2 h = π/27 h^3 dv/dt = π/9 h^2 dh/dt So, plug in your numbers to get dh/dt.
*March 19, 2016*

**Calculus**

h=3r, so r = h/3 v = π/3 r^2 h = π/3 (h/3)^2 h = π/27 h^3 dv/dt = π/9 h^2 dh/dt So, plug in your numbers to get dh/dt.
*March 19, 2016*

**Math**

oops. 56.4% is $146,094.05
*March 19, 2016*

**Math**

multiply 259032 * 0.56 = $145,057.92 Looks like you have a lot of reviewing to do!
*March 19, 2016*

**Math**

the equity is the value less any debts. So, it is 367685-108653 = $259,032 Surely you can figure out 56.4% of that number.
*March 19, 2016*

**math**

is there a question here? I'm no golf expert, but it seems to me that I've always seen negative numbers as below par.
*March 19, 2016*

**math**

LCM(8,10) = 40
*March 19, 2016*

**math series - eh?**

You sure that last value is 1/12, and not 1/24?
*March 19, 2016*

**series**

3 = 1*3 8 = 2*4 15 = 3*5 You sure 1/12 is next? Not 1/24, since 24 = 4*6
*March 19, 2016*

**Calculus**

with height x mm, v = (750-2x)(300-2x)x = 4(x^3-525x^2+56250x) dv/dx = 12(x^2-350x+18750) dv/dx = 0 at x=175±25√19 now pick the one which provides a max, not a min.
*March 19, 2016*

**math**

(2+√7)(2-√7)+√7 4-7+√7 -3+√7 a = -3 b = -1
*March 19, 2016*

**integral calculus**

using shells, v = ∫[0,a] 2πrh dx where r = x and h=2y=4√(ax) v = ∫[0,a] 2πx(4√(ax)) dx = 16/5 πa^3 using discs, v = ∫[0,2a] π(R^2-r^2) dy where R=a and r=x=y^2/(4a) v = ∫[0,a] 2π(a^2-(y^2/(4a))^2) dy = 16/5 πa^3
*March 18, 2016*

**Calculus (Line Integral)**

oops: here is http://math.oregonstate.edu/home/programs/undergrad/CalculusQuestStudyGuides/vcalc/arc/arc.html#alfunction
*March 18, 2016*

**Calculus (Line Integral)**

Actually, just consider the definition of T. Take a peek here, and it should be clear, since the arc length is just ∫ ds = ∫ |dr/dt| dt
*March 18, 2016*

**Calculus (Line Integral)**

Hmmm. Let me dig out my text on differential geometry. Meantime, try googling the topic in vector analysis.
*March 18, 2016*

**Math/Precal**

well, cos(A-B) = cosAcosB + sinAsinB
*March 18, 2016*

**Precal/Math**

Hint: what is 1/(1+u) + 1/(1-u) as a single fraction?
*March 18, 2016*

**Mrs. Sue**

#3 using #2, (B) #4 A=πdh=125.6 so, (C) #5 lateral area is circumference * height = 2πrh
*March 18, 2016*

**Help ASAP**

if the radius is 7 cm, then the area is 4πr^2 = 4π*49 = 615.75 cm^2
*March 18, 2016*

**math help pls pls pls**

the y-intercept is the cost when x=0, or no hours worked. So, the correct answer is C
*March 18, 2016*

**Geometry**

#1: A = 4πr^2 = 4π*1^2 = 4π #2: correct, if the radius is 27cm.
*March 18, 2016*

**math**

well, just list them. If the points are A,B,C left-to-right, then you have 6 ways to pair them up: AB BA AC CA BC CB But the ray going right from A passes through both B and C, so AB and AC are the same ray. Similarly, CB and CA are the same ray. BA and BC point in opposite ...
*March 18, 2016*

**Math/precal**

19π/6 = 3π + π/6 The tan function has period π, so tan(19π/6) = tan(π/6) = 1/√3
*March 18, 2016*

**Math/Precal**

(1-tanx)/(1-cotx) (1-tanx)/(1 - 1/tanx) (1-tanx)/((tanx-1)/tanx) (1-tanx)(tanx) / (tanx-1) -tanx
*March 18, 2016*

**sgfrsargehw**

paha maia
*March 18, 2016*

**physics take 2**

s(t) = s0 + v0t + 1/2 at^2
*March 18, 2016*

**physics**

final speed = 0 easy. just apply s(t) = s0</sub + v0</subt + 1/2 at^2
*March 18, 2016*

**Geometry 5 questions**

#1 D #2 nope #3 nope #4 C #5 B Clearly you need to review these basic transformations. Reflection through the xy plane changes the sign of the z coordinate. xz: change y yz: change x for translations, just add the indicated amounts to the coordinates.
*March 18, 2016*

**Math ASAP**

both correct.
*March 18, 2016*

**Math HELP**

Looks good to me.
*March 18, 2016*

**MATHS**

If the price is p and the cost is c, then 15p = 20c p/c = 20/15 = 1.333 so, he made 33% profit
*March 18, 2016*

**MATH**

#1 B is the only possible candidate, assuming it never repeats #2 well, 150 is not a perfect square #3 do you know your 12 times tables? #4 have you a calculator? try taking the square root 625.
*March 18, 2016*

**1st grade math**

there are probably many online math games he can play. google is your friend.
*March 18, 2016*

**MAth**

well, 2 bundles per foot 3 feet per yard ...
*March 18, 2016*

**math**

150
*March 18, 2016*

**Integer math**

Your answers seem correct, but I fail to see the point of the first two. Find 7 ? answer = 7 ? well, duh. seems kind of bogus to me.
*March 18, 2016*

**math**

23 + 5 × 10 ÷ 2 – 33 + (11 – 8) 23 + 5 × 10 ÷ 2 – 33 + 3 23 + 50 ÷ 2 - 33 + 3 23 + 25 - 33 + 3 48 - 33 + 3 15 + 3 18
*March 18, 2016*

**geography**

diagonal is √(2^2 + 3^2 + 5^2) = √38
*March 18, 2016*

**mathematics-state of rules**

Do you know what the rule is? If not, read http://mathworld.wolfram.com/OsbornesRule.html and the identity is easy to adjust.
*March 18, 2016*

**mathematics-evaluation**

no idea what that means. Do you want the first 5 terms of the power series? e^x = 1 + x + x^2/2! + x^3/3! + x^4/4! + ...
*March 18, 2016*

**Maths**

sin^2 = 1-cos^2, so 4 + 4cos = 1 - cos^2 cos^2 + 4cos + 3 = 0 (cosx + 1)(cosx + 3) = 0 cosx = -1 or -3 -3 is out, so cosx = -1. x = 180 or -180 2sinx = 5cosx tanx = 2/5 x ≈ 21.8° tanx is positive in QI and QIII, so our solutions are x = 21.8° or -158.2°
*March 18, 2016*

**surface area and volume**

how much soil. "many" is used to count individual items, and "much" is used to measure a quantity such as volume. Recall that the volume of a cylinder of radius r and height h is v = π r^2 h Now just plug in your numbers. Volume is in units of m^3.
*March 18, 2016*

**Maths**

These are just quadratic equations. You can factor them as follows: (tanx + 4)(tanx - 1) = 0 (2sinx + 1)(sinx - 1) = 0 Now they are easy, right?
*March 18, 2016*

**Math**

y = x^3-7
*March 18, 2016*

**math**

half a building with 46 is 23. So, 8+B = 2+23
*March 18, 2016*

**another integral...help**

Not sure how to interpret tan^-1/(1+x^2)^2 You don't seem to have a numerator for the fraction. One way, which provides the easiest integration is ∫ x [tan(1+x^2)]^2 dx Let u = 1+x^2 du = 2x dx and you have 1/2 ∫ tan^2(u) du = 1/2 ∫ (sec^2(u) -1) du = 1/2...
*March 18, 2016*

**integration i need**

just expand and divide each term by e^4x. That gives 1/e^4x - 5/e^3x + 10/e^2x - 10/e^x + 5 - e^x That's easy to integrate, recalling that ∫ e^ax dx = 1/a e^ax
*March 18, 2016*

**geometry**

Draw a diagram. Let P be the point where it turned. If it turned θ north of west, then the interior angle at P is 180-θ. Then, by the law of cosines, remembering that cos(180-θ) = -cos(θ), 83^2 + 111^2 + 2*83*111 cosθ = 165^2 Now just solve for θ.
*March 18, 2016*

**geometry**

Use the Law of Cosines to solve the problem. A ship travels due west for 83 miles. It then travels in a northwest direction for 111 miles and ends up 165 miles from its original position. To the nearest tenth of a degree, how many degrees north of west did it turn when it ...
*March 18, 2016*

**maths**

If the faster pipe takes x hours, then we have to look at how much of the pool is filled each hour. 4/x + 9/(x+10) = 1/2 Now solve for x, and then get x+10.
*March 18, 2016*

**math**

7x6
*March 18, 2016*

**algebra**

just put the words into math: 5n+10d+25q = 255 d = n+6 q = 2n now just solve for the values.
*March 17, 2016*

**algebra**

c = a+6 6a+4c = 184 now just solve for the values.
*March 17, 2016*

**Math**

If the different categories have no overlap, then the angle would be that fraction of 360° representing the group of interest. In other words, 190/(190+135+220) * 360 ≈ 125.5°
*March 17, 2016*

**Math**

64m^2 * (1yd/0.9144m)^2 / 13yd * 36in/yd = 211.97 in
*March 17, 2016*

**Geometry**

(e+f)/(a-d) = b/a clear the denominators (also known as cross-multiplying) (e+f)a = b(a-d) or, (e+f)/b = (a-d)/a Looks like the first one is good.
*March 17, 2016*

**Math**

25 3/4 + x = 56 that should help...
*March 17, 2016*

**Math**

their combined speed is 252/4.5 = 56 mi/hr Now you can find the desired speed.
*March 17, 2016*

**math**

a+b+c = 408 b = c+7 b = a+5 now crank it out.
*March 17, 2016*

**math**

49-14 = 35 35/7 = 5 49+35 = 84 84+40 = 124, which is a good estimate
*March 17, 2016*

**Chemistry**

1 molecule of Zn(OH)2 has 3 ions, so the number of ions in 3 moles is 3*3*6.02*10^23
*March 17, 2016*

**Chemistry**

well, 0°C = 273.15°K
*March 17, 2016*

**math help pls pls**

when x=0, the worker has zero hours. So, the y-intercept is the cost of the insurance only. when x=0, 8x+25=25, so the choice is clearly (c)
*March 17, 2016*

**science **

You wish to obtain a magnification of -2 from a convex lens of focal length f. The only possible solution is to?
*March 17, 2016*

**math**

well, it's hard to say. 36/9+48-10/2 = 4+48-5 = 47 36/9+(48-10)/2 = 4 + 38/2 = 4+19 = 23 There are other possibilities, but those two seem the most likely to me.
*March 17, 2016*

**Math**

I don't see the diagram, so I can think of many possible answers, all the way from 45 to 125.
*March 17, 2016*

**music**

#1 surely not A. It is, after all, the KEY SIGNATURE! C is correct. C major is the same key as A minor. #2 cadence is the close of a phrase. C - the phrase is what stands on its own.
*March 17, 2016*

**Math**

correct.
*March 17, 2016*

**mathematics**

Draw radii bisecting both chords. Draw radii to the ends of the chords. Now you have right triangles with the hypotenuse equal to the radius. All the triangles are 5-12-13 So, do the math...
*March 17, 2016*

**Math**

again? See your earlier post. http://www.jiskha.com/display.cgi?id=1458203016
*March 17, 2016*

**Math**

put it all over a common denominator, and you have 2x(2x+3) + 1(x-3) + (3x+9) ---------------------------------- (x-3)(2x+3) as long as x is not 3 or -3/2, the fraction is zero when the numerator is zero. So, now you just have to solve...
*March 17, 2016*

**Math**

see your earlier post: http://www.jiskha.com/display.cgi?id=1458203016
*March 17, 2016*

**math**

Nope. -1 3/4 < -3/4 Better take a gander at C
*March 17, 2016*

**math**

Nope. A is exactly the reverse. Check again on comparing negative numbers.
*March 17, 2016*

**Advance Math**

wolframalpha shows many ways of writing the result: http://www.wolframalpha.com/input/?i=%28ln%283i%29%2F%282%2Bj%29%29^%281%2Fi%29 Using i instead of j, ln(3i) = ln3 + π/2 i = 1.917cis(0.96) 2+i = 2.236cis(0.46) ln(3i)/(2+i) = 0.857 cis(0.50) 1/i = -i, so that is 1/0.857...
*March 17, 2016*

**maths**

By "a 2" I assume you mean one or two 2's. both rolls: 1/6 * 1/6 = 1/36 1st roll only: 1/6 * 5/6 = 5/36 2nd roll only: 5/6 * 1/6 = 5/36 total: 11/36
*March 17, 2016*

**Math**

6: white without stereo dark interior
*March 17, 2016*

**math**

Review how to divide a line segment into 7 equal pieces. Do that for each side, then take 6 of them for the new sides.
*March 17, 2016*

**Maths**

2π*35 cm/rev * 25rev/10s * 1km/100000cm * 3600s/hr = 19.79 km/hr
*March 17, 2016*

**Maths**

If the cylinder's height is H, then we have 1/3 πr^2h + πr^2H = 3 * 1/3 πr^2h πr^2H = 2/3 πr^2h H = 2/3 h
*March 17, 2016*

**maths**

no, log(1) = 0
*March 17, 2016*

**math**

all the outer cubelets have paint. So, reduce the dimensions by 2 to exclude the outer faces, and the inner (paintless) solid is 2x3x5 So, 30 cubelets have no paint.
*March 17, 2016*

**Math**

or, more easily, 5/100 + 12/100 = ?
*March 16, 2016*

**Math**

well the area of a triangle is 1/2 the area of a rectangle with same base and height.
*March 16, 2016*

**Integral calculus**

so, each slice of thickness dx feet of cable weighs 20 dx so, if n feet are pulled up, starting at depth a, the work (force * distance) is ∫[a,a-n] 20 dx You seem to have left out some info.
*March 16, 2016*

**Geometry**

I can't quite grok the figure, but the exterior angles of a quadrilateral add up to 720° so add up all those expressions and set equal to 720, then find x.
*March 16, 2016*

**math**

a = πr^2 r^2 = a/π so, the circumference is c = 2πr = 2π√(a/π) = 2√(22176π) = 527.89 m so the cost is that length times the cost per meter. Your posting has that last bit garbled.
*March 16, 2016*

**Algebra 2**

after t years, you will have 500(1+.065)^t just convert months to years if needed. If the interest is credited at the end of the year, only multiples of 12 months have any effect.
*March 16, 2016*

**mathematics-Algebra**

well, ok. I spoke to soon. Of course, if you know about logs, then 3^x = 9x x log3 = log9 + logx xlog3 - logx = log9 Unfortunately, that isn't any easier to solve than the original equation.
*March 16, 2016*