Thursday

October 27, 2016
Total # Posts: 45,359

**math**

I'll just use x for ease of typing (note the use of parentheses to make things clear!) 1/(1+sinx) + 1/(1-sinx) =((1-sinx)+(1+sinx))/((1+sinx)(1-sinx)) = 2/(1-sin^2(x)) = 2/cos^2(x) = 2sec^2(x) By far the most useful trig identity is sin^2(x) + cos^2(x) = 1 It pops up in ...

*September 23, 2016*

**Math**

well, if they are not equal, one must be less than the other.

*September 23, 2016*

**Calculus**

if you don't know that the slope of the curve is given by the derivative, I suggest more study, or google will provide many discussions. Assuming that you believe that the derivative of a function gives the slope of the curve at any point, then you just have to remember ...

*September 23, 2016*

**Operating System**

once you get past the sloppy English, you might provide a little more information, doncha think?

*September 23, 2016*

**12**

well, the numbers are 2k 2k+2 2k+4 2k+6 multiply them and you have 2^4(k(k+1)(k+2)(k+3)) Now, two of those numbers must be even, so the product is divisible by 2^6 In addition, the product of 3 consecutive numbers is divisible by 6, so 2^7*3 = 384 divides

*September 23, 2016*

**math**

original fraction: (x-3)/x (x-3+4)/(x+4) = 3/4

*September 23, 2016*

**value**

each hour, 1/2 - 1/3 = 1/6 of the tank is filled. That should help some...

*September 23, 2016*

**Maths, science**

maximum volume is achieved when the box is a cube. The area of the box is c^2, so each face has area c^2/6 That means the side has length c/√6. v = (c/√6)^3 = c^3/(6√6) Hmmm. Better double-check my math.

*September 23, 2016*

**Chemistry**

figure the moles each mole fills 22.4L at stp

*September 23, 2016*

**dosage calculations**

looks ok to me

*September 23, 2016*

**Calculus**

f'(a) = R means f(a) = Ra + C But, if f is odd, C=0 So, f(-a) = -f(a) = -Ra

*September 23, 2016*

**Algebra**

reflected: y = |-x| stretched: y = 1.5|-x| shifted: y = 1.5|-x| - 4 However, since |-x| = |x| the reflection has no effect.

*September 22, 2016*

**Math**

48,136.47 / 7

*September 22, 2016*

**Math**

40 + 32.60*8

*September 22, 2016*

**geometry incomplete**

no information on the relative placements of the points.

*September 22, 2016*

**Msth**

300+300

*September 22, 2016*

**taxation**

no, it isn't.

*September 22, 2016*

**Math**

1in : 8ft = 1in : 96in = 1:96

*September 22, 2016*

**Algebra**

oops. Forgot to multiply the 4

*September 22, 2016*

**Math**

you have (almost) listed them in order of distance from zero, but smallest means farthest to the left. And even then, 2.4 is closer than 2 1/2

*September 22, 2016*

**Algebra**

by the time you get to algebra, you should know about fractions ... -2x+1/3y=4 -2(-3) + 1/3 y = 4 6 + y/3 = 4 y/3 = -2 y = -6

*September 22, 2016*

**Math (Plz Help ASAP)**

-7 -7(10*60)

*September 22, 2016*

**math**

the difference is 25 km/hr so, 25*12 km

*September 22, 2016*

**Math**

sloppy use of the = signs, there.

*September 22, 2016*

**Algebra**

|n-0| < 6

*September 22, 2016*

**Math**

well, y = 6x-12 plug and chug 6(-3)-12 = -30 ...

*September 22, 2016*

**PHYSICS**

if the acceleration is in the same direction as the velocity, the object speeds up. Otherwise, the acceleration opposes the velocity, so it slows down.

*September 22, 2016*

**Math**

since ln8 = 3ln2 is just a number, you have ∫(2x^2 ln8)dx = ∫2x^2*3ln2 dx = 6ln2∫x^2 dx = 2ln2 x^3 = ln4 x^3 + C Maybe you had a typo, I'm guessing... If so, recall how to do integration by parts: ∫x lnx dx u = lnx du = 1/x dx dv = x dx v = 1...

*September 22, 2016*

**Physical Science/ Chemistry**

reading down the column, they become more reactive.

*September 22, 2016*

**Math**

so, what two numbers add to 9 and one is twice the other? Come on - there aren't that many pairs that add to 9.

*September 22, 2016*

**Math**

x = amt at 4% x-2000 = amt at 5% Now just compare the interest: .05(x-2000) = .75*.04x

*September 22, 2016*

**MATH**

#1A is correct, but it is not scientific notation for the value. #2B is also correct, but not S.N. #3 is 0.593 x 10^4 But, to make it S.N., you need to have 5.93 x 10^3 #4 5.2 x 10^8 / 25 = 0.208 x 10^8 That is 2.08x10^7 Looks like you need some serious review on how to move ...

*September 22, 2016*

**Physics**

v(t) = Vo + at = 85 - 13t It stops when v=0.

*September 22, 2016*

**Algebra**

stop guessing and start working 1/r * s = s/r, so p=s/r + d p-d = s/r Now what do you think?

*September 22, 2016*

**maths**

depends on the value of y. But, since 12y-12 = 12(y-1) it is certainly not prime.

*September 22, 2016*

**Math**

2.3(4.5-9.6)+3.1 = 2.3(-5.1)+3.1 = -11.73+3.1 = -8.63 you are correct. If your input on the calculator is as accurate as your typing here, it is no surprise that is sometimes wrong...

*September 22, 2016*

**Algebra**

the slope of the perpendicular line is -1/7 So, knowing that the line through (h,k) with slope m is y-k = m(x-h) what do you think?

*September 22, 2016*

**Computing**

I think you mean virtual memory. If so, just google it for many discussions.

*September 22, 2016*

**Math**

incorrect writing as a ratio is just one way of expressing rational numbers. Terminating or repeating decimals is another way.

*September 22, 2016*

**Math**

sorry - you wanted the bearing of Q from X. Just subtract 180°.

*September 22, 2016*

**Math**

since Q to P is 140°, P to Q is 320° P to X is 315°, so angle QPX is 5° using the law of cosines, |QX|^2 = 36^2 + 55^2 - 2*36*55*cos5° = 376.1 So, |QX| = 19.39 km 55^2 = 19.39^2 + 36^2 - 2*19.39*36*cosQ So, Q = 165.7° The bearing of X from Q is thus 140...

*September 22, 2016*

**Physics**

it stops going up when v=0. So, since v = 15 - 9.8t v=0 at t=1.53 So, at t=2.5 it is coming back down: http://www.wolframalpha.com/input/?i=15t+-+4.9t%5E2

*September 22, 2016*

**Physics**

t is 2.5 Vi is 15 m/s up a = -9.8 m/s^2 up (or, 9.8 m/s^2 down) d = Vi * t + a/2 t^2 = 15*2.5 - 4.9 * 2.5^2 = 6.875 m Vf is Vi + at = 15 - 9.8 t^2 (though it does not matter for this question)

*September 22, 2016*

**Math**

x = 2 A = {2}

*September 22, 2016*

**Math - eh?**

{x: x 3x=6} ?? Do you mean {x: 3x=6} ?? Then you ask Does A? Does A what? However, you are correct in saying that {2} is not 2

*September 22, 2016*

**Computer science**

https://en.wikipedia.org/wiki/Virtual_memory

*September 22, 2016*

**math**

(72+84+90)/6 + 90/2 = 86

*September 22, 2016*

**math**

also check out the way the coefficients are sums of subsets of the roots: http://mathforum.org/library/drmath/view/61024.html

*September 22, 2016*

**Mathematics**

list a few how far apart is each from its neighbor?

*September 22, 2016*

**math**

think of the factors of 18 which two differ by 3?

*September 22, 2016*

**Algebra**

x = x/3 + 8 + 52

*September 22, 2016*

**Math**

(1 hr 54 sec) * 7 And yet, I suspect you meant 1 hr 54 min.

*September 22, 2016*

**Algebra**

900/(300+250) hours later

*September 22, 2016*

**Math**

6:8:15 * 7/5 = 42/5 : 56/5 : 21

*September 22, 2016*

**calculus**

x^2+y^2 = 10^2 so, when x=6, y=8 2x dx/dt + 2y dy/dt = 0 Now just plug in your values to find dx/dt

*September 22, 2016*

**math**

14250 * 1.02^3

*September 22, 2016*

**United States History**

thank you

*September 22, 2016*

**United States History**

How is this map different from a typical map of the United States? I couldn't get the map to paste here but it is of the Eastern United States with all the states names crossed out and Irish names put in. circa 1900's I think it was during the potato famine when Irish ...

*September 22, 2016*

**Math**

2P = 3*1000

*September 22, 2016*

**Math**

Since x:y = 7:9, y = 9x/7 (9/7)x = x+10

*September 22, 2016*

**Algebra**

d+t = 48 t+8 = 3(d+8) Now just solve for d and t.

*September 22, 2016*

**Math**

well, does it?

*September 22, 2016*

**Math**

well does it?

*September 22, 2016*

**Geometry**

just take each point and see whether the rule transforms it to the desired point. For example, (x,y+1) transforms (2,4) -> (2,5) Then see which rule takes all 3 points where you want them.

*September 22, 2016*

**Math**

Use the first pair to get the ratio 60/3 = 20 So, for each pair, the 2nd value should be 20 times the 1st value.

*September 21, 2016*

**AP physics**

their combined speed is 1560 km/hr time = distance/speed, so ...

*September 21, 2016*

**Math**

You asked: Determine the number of seats in a bus for each value of r. yet you did not provide any values of r. So, I picked one: 0 Now you pick some others and evaluate 5 + 4xr for each one. I like to help with answers, but don't make me come up with the questions, too.

*September 21, 2016*

**Math**

0: 5 ...

*September 21, 2016*

**algebra**

so far so good: 17/4x = 23/(x+6) now cross-multiply (shorthand for saying multiply by the LCD): 17(x+6) = 23(4x) 17x + 102 = 92x 102 = 75x x = 102/75 = 34/25

*September 21, 2016*

**Math algebra**

hint: think "difference of two squares"

*September 21, 2016*

**MATH HELP**

1C w/o the typo no ideas on the others?

*September 21, 2016*

**Math**

just write their areas as a ratio 24:15 or 8:5

*September 21, 2016*

**algebra**

all ok

*September 21, 2016*

**Math (Geometry)**

statement: if A then B converse: if B then A

*September 21, 2016*

**Math**

a/(1-r) = 100 ar = 24 divide and you have 1/(r(1-r)) = 100/24 r = 2/5 or 3/5 a = 60 or 40

*September 21, 2016*

**Math**

first step: list the possible combinations of coins: 4q, 0d, 1n ... 0q, 0d, 21n Then note how many cannot change $1.00

*September 21, 2016*

**Physics**

a = -45m/s / 9s = -5m/s^2 s = 45t - 5/2 t^2

*September 21, 2016*

**Math**

time to review your basic trig functions. The height h is found by h/100 = tan50°

*September 21, 2016*

**MATHEMATICS**

after t hours, the fraction left is (1/2)^(t/9) So, after 3 hours, there is (1/2)^(3/9) = .7937 of the original amount left.

*September 21, 2016*

**Math**

time = distance/speed, so (400/(150/20)-400/(100/12.5))(100/12.5) = 26.66m

*September 21, 2016*

**Math**

(400/(150/20)-400/(100/12.5))(100/12.5) = 26.66m

*September 21, 2016*

**MATH**

after t hours, the amount left is 2 * (1/2)^(t/5)

*September 21, 2016*

**jay**

nope. And where are your divide symbols? P/2 = l+w now go from there.

*September 21, 2016*

**Calculus**

I assume you want k and m so that g(x) is continuous? Just to make things easier, recall that e^(ln u) = u so, e^(ln(2x+3)) = 2x+3 If so, then you want the endpoints to match: (k(-2)^2)+m = 2(-2)+3 k(3)-m = 2(3)+3 or, 4k+m = -1 3k-m = 9 I guess you can handle that, yeah? As ...

*September 21, 2016*

**math**

20-4-4-4-4-4 = 0

*September 21, 2016*

**Physics**

8.0 m/s^2 * 1km/1000m * (3600s/hr)^2 = 103680 km/hr^2 after h hours, the distances must be the same: 91.0h = 52.0h + 51840h^2 h = 0.000752315 hours = 2.7 seconds Or, you may want to convert km/hr to m/s, but the answer is the same. To get the distance, just plug it into either...

*September 21, 2016*

**math**

well, 2.5 = root(6.25) now just order the squares.

*September 21, 2016*

**Math**

2m^2+m-2m = 2m^2-m = m(2m-1) I suspect a typo, as this does not fit well with the grouping techniques.

*September 21, 2016*

**Math**

I get 4502 counted using bash: for i in `seq 1 11521` ; do echo $i ; done | tr -c -d '3' | wc -c

*September 21, 2016*

**biomechanics**

how long does it take for v to drop to zero? v(t) = 14.27 - 1.67t using that t, the distance moved is s(t) = 14.27t - 0.835t^2

*September 21, 2016*

**Physics**

or, more directly, recalling that the range is R = v^2/g sin2θ just solve for v in v^2/9.8 * sin62° = 8.3

*September 21, 2016*

**Math**

you manage to use + and x, but can't manage / ? 18+9x(5+4)/3-5 18+9x9/3-5 18+81/3-5 18+27-5 ... or 18+9x(5+4)/3-5 18+9x(9/3)-5 18+9x3-5 18+27-5 ...

*September 21, 2016*

**trigonomentry**

not sure what you mean by a "series" of cos, but if you recall your binomial expansions, (a+b)^4 = a^4+4a^3b+a^2b^2+4ab^3+b^4 and then let a=1 and b=cos^2(x), you have sin^8(x) = (sin^2(x))^4 = (1-cos^2(x))^4 = 1 - 4cos^2(x) + 6cos^4(x) - 4cos^6(x) + cos^8(x)

*September 21, 2016*

**Algebra**

well, to get rid of all those words, and use some math, 2u^4*v^2 / 3u = 2u^3v^2/3 or, 2/3 u^3v^2

*September 21, 2016*

**Math**

or, you can think of it like this 27 = 9*3, so 7:9 = 7*3 : 9*3 = 21:27

*September 21, 2016*

**physics**

You need to use the velocity, since distance = speed * time The speed is -15 m/s, so after t seconds, starting from x=30, x = 30 - 15t So, you are correct that x(1) = 15, but after 2 seconds, x(2) = 30 - 15*2 = 0 The object has indeed moved 30m after 2 seconds, but it has ...

*September 21, 2016*

**Geometry H**

E does not matter for this question. Since D bisects the angle, m<CBD = 1/2 m<CBA = 36

*September 21, 2016*

**physics**

you can make this hard (or more general) by setting up distance/speed calculations, and all that, but just notice that the river's speed is 1/2 that of the boat. So, the boat goes downstream 1/2 as far as it goes across.

*September 21, 2016*

**Math :)**

since 120° is 1/3 of a circle, the other two values must add up to 2/3, or twice the 120° value: x+8 = 2(x+2)

*September 21, 2016*

**java programming**

you better learn to read your java documentation. Here's a discussion of the topic: http://stackoverflow.com/questions/17538182/getting-keyboard-input

*September 21, 2016*