Sunday

May 29, 2016
Total # Posts: 40,876

**MATHS**

on each draw, the probability is easy to get. Just multiply them together, as the draws are independent events.
*May 11, 2016*

**MATH**

2/7 * 5/7
*May 11, 2016*

**math**

j=4d j+4 = 3(d+4) now just solve for j and d.
*May 11, 2016*

**Math**

amateur
*May 11, 2016*

**Math **

B looks good to me although technically there is a factor of 100 missing in there, since the answer is really 35%, not 35.
*May 11, 2016*

**MATH**

again? Just add up how many even outcomes there are, and divide by the number of spins. Same problem as before, just different numbers.
*May 11, 2016*

**Math **

right again.
*May 11, 2016*

**Math**

The major axis has length 12, and the center is midway between the two points given, or (1,2) (x-1)^2/16 + (y-2)^2/36 = 1
*May 11, 2016*

**math**

clearly, 102/300
*May 11, 2016*

**Math **

correct
*May 11, 2016*

**Simple Question**

military pay is generally rather low, at least in the beginning.
*May 11, 2016*

**math**

(a) h/126 = tan46° (b) (i) 72/x = tan46° (ii) 72/z = sin46°
*May 11, 2016*

**math**

just use the definition of n! 4! = 4*3*2*1
*May 11, 2016*

**Math**

you don't say which two lines, but I infer that they are x = -1 and x=1. The region is symmetric about the y-axis, so we can just double the area from 0 to 1. using discs, v = 2∫[0,1] π(R^2-r^2) dx where R=e^x and r=e^-x v = 2∫[0,1] π(e^2x - e^-2x) dx...
*May 11, 2016*

**Math**

well, what are 4-3 -2-0 -1-2 ??
*May 11, 2016*

**network programing**

adobe brick? cowhide? more likely lead paint or asbestos But not sure what that has to do with network programming...
*May 11, 2016*

**math**

well, looking at the graphs, it looks like -2 <= x <= 2 checking, if we call them f(x)+g(x) >= h(x), then f(-2) = 20√5 g(-2) = 0 f(2) = 0 g(2) = 20 h(-2) = 28 h(2) = 20 so, f(-2)+g(-2) >= h(-2) f(2) + g(2) >= h(2) Clearly we need x >= -2 for √(x+2...
*May 11, 2016*

**Calculus**

As Reiny says, a rectangle whose base goes from 0 to x has area a = xy = xe^(-x^2) da/dx = (1-2x^2) e^(-x^2) so there is a max at x = 1/√2 That is assuming, of course that the rectangle has its base on the x-axis. It might be possible that a rotated rectangle could be ...
*May 11, 2016*

**Math**

each roll gives 10 possible outcomes, so there are 10^4 events. I ain't gonna list them, but the list starts and ends with 1 1 1 1 1 1 1 1 ... 10 10 10 9 10 10 10 10
*May 11, 2016*

**maths**

well, every second the velocity increases by 0.2 m/s. So how much is that after 10 seconds?
*May 11, 2016*

**Algebra**

no, that is 6.08 x 10^-7 power Move the decimal point to the right for positive powers (multiplying by 10)
*May 11, 2016*

**math**

the diagonal is 90√2=127.28 feet, so the mound is not in the center of the diamond (63.64 ft from home). So, you can't use the Pythagorean Theorem here. Instead, use the law of cosines: x^2 = 60.5^2 + 90^2 - 2*60.5*90*cos45° x = 63.72 feet
*May 11, 2016*

**math**

just use what you know about geometric sequences: S14 = 25(1.1^14-1)/(1.14-1) = 499.55 km
*May 10, 2016*

**Math**

your answer is good, but there are other systems with 3 sets of axes which do the same job. try googling your question. You will see discussions of the other characteristics of the system.
*May 10, 2016*

**Math**

since 1 qt is 1/4 of a gallon, you can go 1/4 as far: 9mi/qt or, using the proper units, get the gallons to cancel: 36 mi/gal * 1gal/4qt = 36/4 mi/qt
*May 10, 2016*

**Math**

18^2 + h^2 = 82^2
*May 10, 2016*

**math: permutations**

correct.
*May 10, 2016*

**Math help ASAP please**

well, plug in t=7. -16*49 + 96*7 = -112 You must be guessing, not calculating. When the ball hits the ground, its height is zero, right? Note that h(t) = -16t(t-6) Now, when is h=0?
*May 10, 2016*

**Math **

come on. You want to land in one of 10 equal areas. The chance is 1/2? Try again.
*May 10, 2016*

**Math**

well, 54+36 = 90
*May 10, 2016*

**math**

Also, sometimes someone comes in and just dumps a lot of homework questions with no indication they plan to do any work on their own. And some questions are so garbled or silly they cannot be deciphered, or do not deserve an answer.
*May 10, 2016*

**math**

usually because no one among the tutors has the particular expertise needed at the time.
*May 10, 2016*

**maths**

because sin(x) is positive in that domain. Your answer is incomplete because you only mentioned QII.
*May 10, 2016*

**Algebra**

so, now it's down to A or D. Do the math...
*May 10, 2016*

**Algebra**

you have 5(2x^3+6x-4) / -5(x-5) = -(2x^3+6x-4)/(x-5) a little synthetic division shows that it does not divide evenly. I suspect a typo. However, it is clear that only B or C could work, even after the typos is fixed.
*May 10, 2016*

**Geometry**

Let M be the midpoint of AD. Then you have two right triangles BMA and DMC where you know the hypotenuse and one leg. Use the Pythagorean Theorem to find BM and MC.
*May 10, 2016*

**Nutz**

–0.5(4 + x) = –1.3 -2.0 - 0.5x = -1.3 -0.5x = 0.7 ...
*May 10, 2016*

**math**

man - have you ever seen the graphs? google is your friend, as is your textbook. both are conic sections, but a parabola has eccentricity = 1 an ellipse has eccentricity < 1
*May 10, 2016*

**MATH HELP PLEASE**

#1 nope. you missed a minus sign #2 could be right, if there was supposed to be a +5 in there #3 nope #4 nope #5 nope. you added, but you should have subtracted. If I ask how much bigger 6 is than 2, you don't add 6+2. #6 nope. you add exponents when multiplying powers. ...
*May 10, 2016*

**Algebra**

collect like terms and you get 8x^2+8x-3
*May 10, 2016*

**Math Please Help**

#1 ok #2 nope. You picked the chance of getting a vowel, but that's not what they asked. #3 ok #4 ok #5 ok
*May 10, 2016*

**Analytic Geometry**

you know it has a double root at x=0 so, the graph is tangent to the x-axis at (0,0) The graph crosses the x-axis at x=4 y is positive for large negative values of x, so the graph comes down from the left, touches (0,0), goes back up and crosses at (4,0) on its way down to the...
*May 10, 2016*

**calculus**

Hmmm. I misspoke. The average value is ∫[0,2] V(t) dt -------------------- 2-0 = 0.3010
*May 10, 2016*

**calculus**

That would just be (V(2)-V(0))/(2-0) = 0.6554/2 = 0.3277
*May 10, 2016*

**Linear Algebra - urgent!**

google is your friend. You could start here: http://math.stackexchange.com/questions/986859/why-is-deta-lambda-i-lambda-cn-when-a-cin-0
*May 10, 2016*

**Algebra 2**

not quite sure what you mean by t time is on 120 sec From what you said, it appears that h = at^2 + 35000 But, from the two data given, it looks like h(120) = 35000
*May 10, 2016*

**Math**

well, jeez - look at the 7 row. How many 8's are there?
*May 10, 2016*

**Maths grade 12**

of course , if siny = 0, then we have cosy = 1 or -1. You can try those for other solutions.
*May 10, 2016*

**Math (please help)**

the box is 8" long, so the paper has to be long enough to wrap around the ends. I'd say (D)
*May 10, 2016*

**math**

center is at (-6,5) so (x+6)^2/a^2 + (y-5)^2/b^2 = 1 The semi-major axis is vertical,and of length 13. c^2 = a^2-b^2 165 = 169-4, so b=2 (x+6)^2/4 + (y-5)^2/169 = 1 see http://www.wolframalpha.com/input/?i=ellipse+%28x%2B6%29^2%2F4+%2B+%28y-5%29^2%2F169+%3D+1
*May 10, 2016*

**maths**

recall that the product of the roots will be f/1 If f is prime, then the only possible rational roots will be ±1, ±f Since f and -f cannot both be roots (why?) there can be at most 3 rational roots. Furthermore, since f is positive (why?), -1 cannot be a root, ...
*May 10, 2016*

**calculus sir damon help me or steve**

recall your half-angle formulas for hyperbolic functions: sinh(x/2) = √((coshx-1)/2) so, √(coshx-1) = √2sinh(x/2) dx/√(coshx-1) = 1/√2 csch(x/2) dx now just use your standard form for integrating csch(u)
*May 10, 2016*

**math**

k = .6l l = .6m m-140 = l now just find k+l+m
*May 10, 2016*

**math**

a+b=108 3a/4 + (2/5)(b+a/4) = (3/5)(b+a/4) now just solve for b.
*May 10, 2016*

**geometry and trig**

If the cylinders are similar, then the ratio of volumes is (10/4)^3 as much, or 15.625 lbs = 250 oz how did you get 137pi? I suspect something is left unsaid here, as none of the choices seems right.
*May 10, 2016*

**algebra 1**

well, he is 1.75 std above the mean, or 28 + 1.75 * 8
*May 10, 2016*

**Mayh**

1/2 of 1/2 = 1/4
*May 10, 2016*

**math: probability**

wrong.
*May 10, 2016*

**math: probability**

correct, if you replace the first card before drawing the second.
*May 9, 2016*

**Algebra**

ignoring the mysterious comma, 3fg(f^2+5f-4) = 3f^3g + 15f^2g - 12fg
*May 9, 2016*

**math**

sounds like a rectangle to me.
*May 9, 2016*

**Science**

the same
*May 9, 2016*

**calculus**

(lnx)/(x) x^(lnx-1) = x^(lnx)/x
*May 9, 2016*

**calculus**

Is the lnx/x suppose to be (lnx)/(x) or ln(x/x)?
*May 9, 2016*

**calculus**

I don't understand how you went from y' = lnx x^(lnx -1) + lnx x^lnx (1/x) to lnx/x x^lnx + lnx/x x^lnx. Where did the -1 go? May you please explain?
*May 9, 2016*

**calculus**

recall that d/dx x^n = n x^(n-1) d/dx a^x = lna a^x so, if y = u^v, y' = v u^(v-1) u' + lnu u^v v' Here you have u = x v = lnx So, y = x^lnx y' = lnx x^(lnx -1) + lnx x^lnx (1/x) = lnx/x x^lnx + lnx/x x^lnx = 2lnx/x x^lnx or, do it like this y = x^lnx lny = lnx...
*May 9, 2016*

**calculus**

Find dy/dx. y = x^ln x, x > 0
*May 9, 2016*

**Math**

well, geez - did you plug in the values? y(0) = 5, so it will end in +5 1^2 = 1, so y = -x^2 + 5 so, yes, B is the answer.
*May 9, 2016*

**Algebra**

y = kxz 4 = k*4*1 k = 1 y = xz
*May 9, 2016*

**Algebra**

If the point is x miles from NYC, then since time = distance/speed, (3458-x)/(850+50) = x/(850-50)
*May 9, 2016*

**math**

Assuming you actually replace the 1st ball before drawing the 2nd, then the chance of drawing a green ball in at least one of the draws is the complement of drawing no green ball either time. The chance of no green ball twice in a row is 50/70 * 50/70 = 35/49 So, the chance of...
*May 9, 2016*

**Differentiation**

again?
*May 9, 2016*

**maths**

2(70 + 80+20) - 2(70+80) = 2(20) = 40 m or, 20m on each long side...
*May 9, 2016*

**Differentiation**

A = 3t^2 + 7 dA/dt = 6t now plug in t=5
*May 9, 2016*

**Math**

q = d+8 n = d-5
*May 9, 2016*

**Algebra**

Since time = distance/speed, 66/(r+7) = 24/r
*May 9, 2016*

**math**

1 + 6/16 = 1 + 3/8 = 1 3/8 can't see how that would have caused you any trouble...
*May 9, 2016*

**physics**

mv1 = <0,-144> mv2 = <-270/√2, 270/√2> add the vectors and then change back to direction and magnitude.
*May 9, 2016*

**functions**

A little division shows that 6x^3-ax^2+bx+c / (x+4) has a remainder of -16a-4b+c-384 6x^3-ax^2+bx+c/(x^2-4) has a remainder of (b+24)x+c-4a So, -16a-4b+c-384 = -220 b+24 = 23 c-4a = -26 solve those and you get f(x) = 6x^3 + 31/2 x^2 - x - 88 You can verify the remainders for ...
*May 9, 2016*

**MATHEMATICS**

geez, impatient much?
*May 9, 2016*

**MATH**

Draw a diagram. The distance x between the tree and pole can be found using 10.65/x = tan60° Then the remaining height y of the top of the tree and the top of the pole is found by y/x = tan46°
*May 9, 2016*

**math**

set it up in the usual way x^2-x+2 = 0 b^2-4ac = 1-8 = -7 so, what does a negative discriminant tell you?
*May 9, 2016*

**Geometry**

could be, depending on where the docks are. The docks could be anywhere from 0 to 40 yards apart.
*May 9, 2016*

**algebra**

good as far as you went, but 10/√27 10/(3√3)
*May 9, 2016*

**math**

sinA = 2 sinA/2 cos A/2 similarly for B and C Now add them up.
*May 9, 2016*

**math,science**

a = -22m/s / 13s = -22/13 m/s^2
*May 9, 2016*

**geometry**

you can easily see that the region is a rectangle. Rotate a rectangle around one of its sides and you get a cylinder. Then it's easy. See my work at http://www.jiskha.com/display.cgi?id=1462581546
*May 9, 2016*

**math**

This may help: http://mathforlove.com/2012/02/midpoints-of-a-quadrilateral-form-a-parallelogram/
*May 9, 2016*

**math**

the interest is the same for each year: 13000 * 0.08 clearly you need to review why the "normal" method works as it does.
*May 9, 2016*

**Algebra II**

well, π radians = 180°
*May 9, 2016*

**Algebra II**

use the law of sines
*May 9, 2016*

**geometry**

If they have the same base area, then the volumes are in the ratio of the heights, cubed. That is 250/2 = (H/h)^3
*May 9, 2016*

**Algebra II**

did you draw a diagram? If so, you can see that the distance x is found using the law of cosines: x^2 = 3.6^2 + 2.3^2 - 2*3.6*2.3*cos66˚
*May 9, 2016*

**math**

There are 20 greens in 70 gumballs The chance of drawing zero green ones is 50/70 * 49/69
*May 9, 2016*

**math**

the two terms are 9d apart. So, d = -2 Now you have d, and can easily find a, so S15 = 15/2 (2a + 14d)
*May 9, 2016*

**math**

huh?
*May 9, 2016*

**Trigonometry**

the height in feet can be found using h/5280 = tan6°
*May 8, 2016*

**Geometry**

V = 18*w*12 where the width is w.
*May 8, 2016*

**math: pre-calculus**

by definition, e^(ln x) = x ln(e^x) = x ln and e^ are inverse functions, just like x^2 and √x Assuming no typos, I see ln(e^3y)+ln(ey)-ln(e^4) = ln(e^3y * ey / e^4) = ln(y^2) = 2ln(y)
*May 8, 2016*

**math: pre-calculus**

you want p = a e^(kt) clearly p(0) = 53 p = 53 e^(kt) p(3) = 90, so 53 e^(3k) = 90 e^(3k) = 90/53 3k = ln(90/53) k = ln(90/53)/3 = 0.1765 so, we have p(t) = 53 e^(.1765t) Now you try the others, lest you be accused of homework dumping...
*May 8, 2016*