Saturday

July 30, 2016
Total # Posts: 42,174

**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*

**Math**

If C is the circumference of the earth, in inches, then that would be 6.7*10^9 * 12 / C So, look up C.
*June 13, 2016*

**math**

That would be correct.
*June 13, 2016*

**math**

ok, the next step is (x-6)(x+1) = 0 x = 6 or -1 Now just find y for each of those x values.
*June 13, 2016*

**math**

equate y and you have x^2-6x+7 = -x+13 x^2-5x-6 = 0 and I think you can take it from there, yeah?
*June 13, 2016*

**Math**

N = kA/P That mean that NP/A = k, a constant So, you want to find N such that 50N/65 = 50*12/50 where we have expressed A and N in thousands
*June 13, 2016*

**math**

p(1+18(r/12)) = 10450 p(1+2r) = 10600 (1 + 3r/2)/(1+2r) = 10450/10600 r = 0.03 now use that in either equation to find p.
*June 13, 2016*

**Calc**

using l'Hospital's Rule, the limit is the same as that of 2√x / √(1+2x) --> 0
*June 13, 2016*

**rout**

maybe they're separate problems. In that case, just use the normal formula v = π/4 d^2 h and use your numbers
*June 13, 2016*

**Science**

I assume you mean the number doubles every 20 minutes. In that case, after n periods of 20 minutes, there will be 100*2^n bacteria. So, how many times have they doubled in 2 hours?
*June 13, 2016*

**Mathematics**

just look at the information given: 7s+3h = 50 3s+2h = 24 now you take over...
*June 13, 2016*

**math**

sure looks like C to me did you try dividing dollars by months for some rows? They are all the same.
*June 12, 2016*

**Math**

recall your basic equation of motion: y = 300 + 500t - 4.9t^2
*June 12, 2016*

**math**

the values are correct. As the number of iterations grows, so does the f value, either positive or negative. And that's 2^x 2x means 2 times x: 2,4,6,8,...
*June 12, 2016*

**math**

irrational, real
*June 12, 2016*

**math**

it is integer, rational, real as to why, you'd better review the categories.
*June 12, 2016*

**Calculus**

since pi/x < pi/2 for this limit, tanθ will be positive so the limit is +∞
*June 12, 2016*

**Math**

well, where does sinx = cosx? Divide by cosx, and you have tanx = 1 Look familiar?
*June 12, 2016*

**math**

No way to tell. At most 36 runners, though.
*June 12, 2016*

**math**

not quite. You have to watch the units. 10 seconds is 1/360 hours.
*June 12, 2016*

**math**

well, how far does the hare go? distance = speed * time
*June 12, 2016*

**math**

probably the latter, as the previous post used half-angle formula. So, eku, I guess that gives a clue to this one, too, eh?
*June 12, 2016*

**maths**

x+y+z = 26 y = 3x You want minimal x^2+y^2+z^2, so check out a few possibilities: x y z ∑*^2 1 3 22 488 2 6 18 332 3 9 14 208 ... I think you can figure it out.
*June 12, 2016*

**math**

use your half-angle formula: tan(A/2) = (1-cosA)/sinA you can easily find cosA, and then just plug and chug.
*June 12, 2016*

**Maths**

Draw the unit circle. Draw a right triangle in standard position (right angle on the x-axis). Now label the sides. The hypotenuse is 1 The height is x Let angle A be at (0,0) So, sin(A) = x/1 = x That is, A = sin^-1(x) csc(A) = 1/sin(A) = 1/x So, A = csc^-1(1/x)
*June 12, 2016*

**math**

so, what's the problem? Get out your protractor and ruler.
*June 12, 2016*

**math**

upstream time is m/(r-s) downstream time is m/(r+s)
*June 12, 2016*

**Math**

something is messed up. I suspect a typo. In particular, I think 4.6 cakes will take a lot more than 3/5 lb of flour, unless they are very small cakes. Hmmm. 2/3 lb is about 3/5 cup. I know I can't make 4 cakes with that much flour!
*June 12, 2016*

**Math**

suppose you know how much you need to make 3 cakes. To make one cake, you just divide by 3, right? So here, just divide by 4 3/5. (2/3)/(4 3/5) = (2/3)/(23/5) = 2/3 * 5/23 = 10/69 All fractions work the same way.
*June 12, 2016*

**Algebra**

Usually people don't talk about "prime factors" of polynomials, but a complete factorization should do the job. Here are a few: a. 2a^2 - 2b^2 = 2(a^2-b^2) = 2(a-b)(a+b) b. 6x^2 - 6y^2 = 6(x^2-y^2) = 2*3(x-y)(x+y) c. 4x^2 - 4 = 4(x^2-1) = 2*2(x-1)(x+1) d. ax^2 - ...
*June 12, 2016*

**Physics**

so, did you draw the path? where did you end up? Hint: label the start (0,0) Distance covered is just the sum of all the line segments. Final displacement is found using the normal distance formula, which is just the Pythagorean Theorem.
*June 12, 2016*

**Trigonometry**

nothing to do but convert to x-y form, add them up, and then convert back. Luckily, they can be treated as complex numbers, making the job easier, using polar form. And, you can let wolframalpha.com do all the work (or any other handy calculator you know). You can check your ...
*June 11, 2016*

**Mathematics**

Nope. The A+B+C=180 Note that the sides AC = b AB = c Use the law of cosines to get a^2 = b^2+c^2-2bc cosA Now, having a, you can use the law of sines to get A: sinA/a = sinC/c
*June 11, 2016*

**Math - Year 10 - Simult. equations**

you know that 4y = -3x, so use that in 16x^2 + 16y^2 = 400 16x^2 + (4y)^2 = 400 16x^2 + 9x^2 = 400 and I think you can take it from there, right?
*June 11, 2016*

**pre-algebra**

Interesting. As a position relative to the surface, the value is -550. But, as you say, the depth is indeed 550 ft. "Depth" carries with it an implied negative value. I'd check to see just how they want you to interpret positive and negative quantities.
*June 11, 2016*

**Math**

best bet is to convert all to decimals. The it will be easy. SO, 2/3 = 0.6666 0.2 = 0.2000 and so on
*June 11, 2016*

**Algebra**

(a+b)(a+b) Now just expand that us usual
*June 11, 2016*

**maths**

if two polynomials have the same roots, one is a multiple of the other. So, x^2+px+q = 2(x^2-(5/2)x-(3/2)) so, p = -5/2 and q = -3/2
*June 11, 2016*

**maths**

If the roots are p and q, then we have pq = k Since p = 1/q, pq = 1 So, k=1 x^2-5x+1 has roots (5±√21)/2 I leave it to you to verify that the two values are reciprocals.
*June 11, 2016*