Tuesday

August 30, 2016
Total # Posts: 42,911

**Calculus**

you can find the area B of the base (a triangle), and its height (the z-intercept) v = 1/3 Bh
*June 20, 2016*

**Math (pre-celc 12)**

the order does not matter. There are 21P3 ways to select an ordered group of 3 items from 21. Whoever is chosen first, there are 21 available people. 20 for the 2nd, and 19 for the 3rd.
*June 20, 2016*

**Math**

So far you have only mentioned 4 places. Any data on the other three? A lot of possibilities will fit what you have required so far.
*June 20, 2016*

**physics**

10+12 √(10^2+12^2)
*June 20, 2016*

**algebra**

2x+2x+2+2
*June 20, 2016*

**Science chemistry**

I only found TETRACHLOROMETHANE
*June 20, 2016*

**Maths**

(n+1)/d = 1/3 n/(d+1) = 1/4 If that's too hard to work through, then just consider that 5/15 = 1/3 4/16 = 1/4
*June 20, 2016*

**Mathematics**

14000(1+.12)^2 vs 14000(1+.12/2)^(2*2)
*June 19, 2016*

**math**

2(r^4-1)/(r-1) = 30 r=2 The last 4 terms don't matter, unless you are interested in how many there are.
*June 19, 2016*

**Math**

t+b+f = 7.56 f = 2t 1.1t + 1.25b + f = 8.68 Now just crank out the desired answers
*June 19, 2016*

**Maths**

w/250 = cot50°
*June 19, 2016*

**Physics**

How can you explain work, in regards to electricity? I understand it as the product of energy used, usually displacement. I cant understand or explain it as far as electricity is concerned. I'm not sure if I understand it at all.
*June 19, 2016*

**Math**

oops. 2sin^2(1/2 y) = 1 - cosy
*June 19, 2016*

**Math**

f(x+y)-f(x) = sinx cosy + cosx siny - sinx sin^2(1/2 y) = 1 - cosy That should get you on your way... The rest is just algebra.
*June 19, 2016*

**trigonometry**

draw a diagram review the tan function see that tanθ = 36/20
*June 19, 2016*

**Maths**

It never hurts to review. I help students with advanced algebra and calculus, and am constantly amazed and frustrated at how much of their elementary arithmetic they have forgotten. Look over your topics, try out some problems, and make sure that when you see them you don'...
*June 19, 2016*

**math**

if sinθ = 1/3, 2cot^2θ + 2 = 2csc^2θ = 2(3)^2 = 18 = (9)+(224) = 233
*June 19, 2016*

**math**

just subtract (5x^3-13)-(2x^3-4x+9) = 3x^2+4x-22
*June 19, 2016*

**mathematics**

.0x0 .3x1 .6x2 .9x3 .000 .341 .682 Can't pin it down any better than that
*June 19, 2016*

**Math 5**

If there were 15 correct answers, then there were 5 wrong, so 15*5 + 5*2 = ?
*June 18, 2016*

**math**

Tn = 2n
*June 18, 2016*

**Math**

1.4/7
*June 18, 2016*

**Math**

The speeds are x and x+8 since distance = speed * time 60(x + x+8) = 4320
*June 18, 2016*

**math**

a = 5-2√6 a^2 = 49-20√6 1/a^2 = 49+20√6 Now just add up a^2 + 1/a^2
*June 18, 2016*

**Mathematics**

surely you can do some of those. Which ones present a problem? area of sector: 1/2 r^2 θ arc length: rθ
*June 18, 2016*

**Mathematics construction**

ok now what? Surely you can bisect a 90-degree angle...
*June 18, 2016*

**math @Reiny**

oh, yeah. Good call.
*June 18, 2016*

**math**

well, geez, just plug in the values. You have (x-1)(x+3) = x^2 + 2x - 3 = x^2 + (a+1)x + b Now it should be clear what a and b are if the two polynomials are identical.
*June 18, 2016*

**math**

If I read you right, we have v^2 + 4√3 v - 15 = 0 (v-√3)(v+5√3) = 0 Not sure what you mean by "its coefficient".
*June 18, 2016*

**Science**

it is at its highest when the velocity drops to zero and it starts to fall. v = Vo - at = 98 - 9.8t ...
*June 18, 2016*

**math**

see earlier post
*June 18, 2016*

**physics**

F = ma now just plug in your values.
*June 18, 2016*

**area of a circle**

clearly the radius is 3, since that's how far away the point is from the x-axis, right? Now crank it out.
*June 18, 2016*

**Algebra**

well, they have said that a=3 r=5 The 23rd term is thus 3*5^22 That is, you start with 3 and multiply by 5 22 more times to get to the 23rd term. Next, we have a + 7*4 = 13 so, a = -15 T23 = -15 + 22*4 Any two consecutive terms of a geometric sequence have a common ratio. In ...
*June 17, 2016*

**math**

The multipliers are 1,3,9,27, ... As powers of 3, those are 0,1,2,3,... You can't say 7*3^x because the first term (x=1) has not been multiplied yet.
*June 17, 2016*

**math**

I can see only (5,-5) and (-5,5) any other pairs of additive inverses do not differ by 10
*June 17, 2016*

**Math**

terms of what?
*June 16, 2016*

**math**

since mass is proportional to volume, the ratio would be (15/25)^3
*June 16, 2016*

**Maths**

well, 3/7 + 5/8 * 4/7 = 11/14
*June 16, 2016*

**maths**

2(24+84)/3 * 100
*June 16, 2016*

**math**

4/3 pi r^3 = 1200 cm^3 r^3 = 900pi cm^3 ...
*June 16, 2016*

**Math**

pi r^2 = 9.5 c = 2pi r = 2pi √(9.5/pi) = 10.93 m
*June 15, 2016*

**Calculus**

how about some parentheses, so we know what's where? Also, it would be polite to indicate just what it is you want to know. For starters, just enter your expression in the box at wolframalpha.com and it will show you the graph, its derivative and integral, and more. Be ...
*June 15, 2016*

**math**

at 1 pm Train 1 had gone 300 miles. Now you know that one train is going 5/4 as fast as the other. see what you can do from here.
*June 15, 2016*

**physics**

font is garbled. Try explaining. review dot and cross products
*June 15, 2016*

**math**

2 hrs at 50km/hr = 100 km So, how long does it take to go that far at 40 km/hr?
*June 15, 2016*

**math**

a 180° rotation (in either direction) just changes the signs of all the coordinates.
*June 15, 2016*

**Algebra**

surely you are not saying that those two answers are equivalent. (2±√10)/2 is the correct solution. If you try plugging in 2√10 you will see that it does not do the job.
*June 15, 2016*

**Math**

NYC = 10 ~NYC = 90 NYC & 18 = 10 ~NYC & 18 = .70*90 = 63 Knowing that there are 73 18-yr-olds, and that 10 of them are from NYC, ...
*June 15, 2016*

**Math**

if the speed of the prop is x, then the jet is 4x. Since distance = speed * time, we have 4x*2 + x * 1/2 = 850
*June 15, 2016*

**math**

ok. I assume you want to know what x is. Well, we know that 8.50x < 54-20
*June 15, 2016*

**Math**

A √(100^2+185^2+7^2) = 210.4 km B tanθ = 7/√(100^2+185^2) so, θ=1.9°
*June 15, 2016*

**maths**

you have the formula, right? So plug in your numbers.
*June 15, 2016*

**maths**

1/4 of 16 = 4 1/2 of 16 = 8 after giving those away, he had 4 left. How did you arrive at your answer?
*June 15, 2016*

**Algebra**

pay attention to which variables are paired together, and just add up like terms. For example, the cd terms are 4-(-9)+1-1 = 13cd
*June 15, 2016*

**Algebra**

just working with the x² terms, we have -3+2-5 = -6x² do the x's and constants the same way.
*June 15, 2016*

**CALCULUS**

done two days ago: http://www.jiskha.com/display.cgi?id=1465840275
*June 15, 2016*

**Algebra**

the minimum number of pieces assumes no mistakes, so 30x >= 320
*June 15, 2016*

**math**

6+2*5
*June 15, 2016*

**math**

surely you can list all pairs of digits whose sum is 9. Then just make sure that the 2nd digit is odd, and you're done. Note that the first digit must be even, if the sum is odd. The first in your list will be 27 and you can surely list the others.
*June 15, 2016*

**math**

just make sure the values are equal: 1.20x + 0.90*2 = 1.00(x+2)
*June 15, 2016*

**math**

In terms of pints used, .30*4 + .20*3 = x(4+3)
*June 15, 2016*

**maths class 6**

so, did you do any of what was asked?
*June 15, 2016*

**Math**

how cub? 9*12*0.60 is one possible answer.
*June 15, 2016*

**math**

at time t hours after noon, we have the distance (starting at k km) is z^2 = (k-30t)^2 + (15t)^2 2z dz/dt = -60(k-30t) + 450t dz/dt = (2250t-60k)/(2z) = 15(75t-2k)/z dz/dt=0 when t = 2k/75 so it depends on how far apart the ships were at noon.
*June 15, 2016*

**Math**

If n is the smaller, then we have n + 5n-6 = 12
*June 14, 2016*

**maths**

25.75 km/l * 7l = 180.25 km
*June 14, 2016*

**maths**

so, how many sevenths are there in a whole apple? Eat one, and how many are left?
*June 14, 2016*

**algebra**

wrong. y=2, so it should go 2x+4(2)-6 = 0 2x+8-6 = 0 ... and that's "ordered pair", not "repair"
*June 14, 2016*

**math**

any book on trig will show this graph, and explain all the above topics. Where do you get stuck?
*June 14, 2016*

**Algebra 1**

a little synthetic division shows that it is 2
*June 14, 2016*

**math**

2583/3 = 861 so, that is the middle number
*June 14, 2016*

**Math**

not unless it does symbolic math. wolframalpha.com is a nice online calculator you can use for this stuff
*June 14, 2016*

**Math**

fastest increase rate is where the slope is steepest. That is, you want a maximum for f'(x). That happens where f"(x) = 0 f = 2cos(2x) f" = -8cos(2x) f"=0 when x=π/4, 3π/4 and so on. The slope is negative at π/4, so you want x = 3π/4 A ...
*June 14, 2016*

**Math**

did PsyDag's comment not help you? He told you what to do at each step. Can you not turn that into a function? For example, if you add 3 at each step, after x steps, you have added 3x to the initial value.
*June 14, 2016*

**geometry**

x and y will be halfway from one end to the other. That is just the average of the two end values.
*June 14, 2016*

**math**

7600(1+.15*25) vs 7600(1+.15)^25 Where do I sign up for that interest rate!?!
*June 14, 2016*

**Physics**

no diagram, but just convert each vector to x-y coordinates, and then add them up. then convert back to polar form.
*June 14, 2016*

**math trigo**

that's alpha, beta, theta If I read you right, we have θ = α+β tanx/tany = x/y prove: sin(α-β) = (x-y)/(x+y) sinθ well, sinθ = sin(α+β) so now we can say we want sin(α-β)/sin(α+β) = (x-y)/(x+y) note that sin(...
*June 14, 2016*

**Math**

140/x = 7/11
*June 14, 2016*

**math**

T5 + T24 = 50 a+4d + a+23d = 50 a + a+4d+23d = 50 a + a+27d = 50 T1 + T28 = 50
*June 14, 2016*

**Math**

draw your number line mark -3 and 3 now count the intervals between the two numbers.
*June 14, 2016*

**math**

volume = area of base * length I assume you can find the area of a triangle.
*June 14, 2016*

**Math**

how about using real math symbols? f(x) = (2x-2)^2 - 3x^2 + 6 = 4x^2 - 8x + 4 - 3x^2 + 6 = x^2 - 8x + 10 Now you need a perfect square. = x^2-8x+16 + 10-16 = (x-4)^2 - 6
*June 14, 2016*

**math**

2+8-14+2 = ?
*June 14, 2016*

**Calculus**

The x values given are the right-left edges of the rectangles. You want right-side values, so figure f(x) at x = 9,11,14,15 Multiply each height by its interval's width, and the approximation is just 5*11+2*18+2*21+1*25 = 158 So, the average height is the area divided by ...
*June 14, 2016*

**math**

the radius i 7, so its circumference is 14π. Now just divide the length rolled by the circumference.
*June 14, 2016*

**Calculus- PLEASE HELP**

xy = 1334, so y = 1334/x 3(x-6)(y-6) = 2760 3(x-6)(1334/x - 6) = 2760 solve that and you get x = 29 or 46 so, the original sheet was 29 by 46 in. v(x) = (24012+4110x-18x^2)/x = 6(x-6)(667-3x)/x for v>0, we have 6 < x < 667/3 Makes sense, since we can't cut two 3&...
*June 14, 2016*

**Math , new Oxford public school.**

1/6 y = 3 - 1/7 x so, 1/3 y = 6 - 2/7 x Now use that in the other equation: 1/2 x - (6 - 2/7 x) = 5 11/14 x = 11 x = 14 or, you can use elimination. since 1/3 = 2/6, 2/7 x + 1/3 y = 6 1/2 x - 1/3 y = 5 Now add the two equations to get rid of the y: 11/14 x = 11 so, x = 14 Now ...
*June 14, 2016*

**Maths**

If there were p to start with, p(1-0.20-0.05)(1-0.45) = 33 p = 80 check: 20% of 80 is 16 gone 5% of 80 is 4 dead so, that leaves 60 45% of 60 is 27 sold That leaves 33
*June 13, 2016*

**Math**

depends on what the amount was at the start. But, 2^10 = 1024
*June 13, 2016*

**Math**

the rolling area of the cylinder is 84*120π cm^2 = 3.17 m^2 now just divide.
*June 13, 2016*

**Math**

7km/25min * 60min/hr = 420/25 km/hr = 16.8 km/hr If he says the speed is 28km/hr, he's working on some other problem. if there are various speeds, the average speed is the total distance divided by the total time.
*June 13, 2016*

**math**

just multiply 150 by the number of minutes in an hour or day.
*June 13, 2016*

**Algebra**

-11√112 = -11√(16*7) = -11√16√7 = -11*4√7 = -44√7
*June 13, 2016*

**Algebra**

if all you want to do is expand the factors, then recall that (x^m)^n = x^(mn) so, that gives you (4ah^2)^3(ah)^5 = 4^3 a^3 h^6 a^5 h^5 = 64 a^8 h^11
*June 13, 2016*

**math - eh?**

it would be nice if you asked a question, instead of just posting gibberish. At first I thought you wanted to solve two simultaneous equations: 1/2 (2x+3y )+12/7 (3x -2y )=1/2 7/(2x +3y )+4/(3x -2y )=2 but that became unwieldy fast. Are you trying to clear fractions? 1/2 (2x+...
*June 13, 2016*

**algebra**

recall that the line through (h,k) with slope m is y-k = m(x-h) Now just plug in your values.
*June 13, 2016*

**Algebra**

assuming direct variation, y = kx so, k = 2/3
*June 13, 2016*