Thursday

August 27, 2015
Total # Posts: 33,098

**science**

the value does not change when you multiply it by 1. So, write 1 in the ways you need to get the units you want: 100km/hr * 1000m/km * 1hr/3600s = 27.778 m/s
*July 4, 2015*

**Java**

You really need to learn how to consult your java documentation, or at least use google. I did a search for "java loop" and found this in 5 seconds: while( x < 20 ) { System.out.println("value of x : " + x ); x++; } I'm sure you can adapt it to your ...
*July 4, 2015*

**lazy spelling, vague math question**

care to be a bit more specific on just what it is you want to solve? And we're not here to check our ability -- we're her to help with homework problems. Why don't you show us how far you got, and where you get stuck?
*July 4, 2015*

**geometry**

π*8(8+15) And that's pi, not pie! Pie is what you eat.
*July 4, 2015*

**Physics**

sorry, no graphs here. No doubt a google search will turn some up for you to look at. If calculus is something you have studied, the result is almost trivial.
*July 4, 2015*

**Physics**

how long does it take to fall 11m? 1/2 at^2 = 11 Then it takes the sounds 11/343 s to come back.
*July 4, 2015*

**Sorsogon state colleges**

If it fell to ground after 6 seconds, then it was at its maximum height after 3 seconds. So, how far does a ball fall in 3 seconds? s = 1/2 at^2
*July 4, 2015*

**science**

acceleration is (25m/s)/(10s) = 2.5 m/s^2 distance during acceleration: s = 1/2 at^2 = 125m so, total distance is 125 + 10*25 = 375 m
*July 4, 2015*

**irshad**

Some do.
*July 4, 2015*

**Basic Computer Science**

There are lots of java snippets online. Here's something that should work: public static void xx(int n1, int n2) { if (n1 == n2) System.out.println(n1*n2); } It can be prettied up some, but that's basically all you need.
*July 3, 2015*

**Math**

c+s+a = 170 5c+6s+8.50a = 970 c = 2s I expect you can take it from there, right? And why specify that student tickets are "all day"? Are the others restricted in some way?
*July 3, 2015*

**munali boys**

y = k x^2 √z Or, y/(x^2 √z) = k and is constant. So, 3/(4^2 √9) = y/(3^2 √16) Now just solve for y.
*July 3, 2015*

**Math**

very likely false.
*July 3, 2015*

**Math equation**

A = wL Unusual, when the width is longer than the length.
*July 3, 2015*

**calc**

why all the words? dy/dx = x/y^2 clearly in QI,IV all the slopes are positive in QII,III all the slopes are negative at the x-axis, all the tangents will be vertical, but anywhere else they will not be. See http://www.wolframalpha.com/input/?i=slope+field&a=*C.slope+field-_*...
*July 3, 2015*

**Physics**

it takes 0.326 seconds for the water to fall 52 cm. So, the horizontal speed is 100cm/.326s = 306.9 cm/s
*July 3, 2015*

**math**

polynomials of odd degree have range (-∞,+∞) if the polynomial has even degree, say 2k, then x^(2k) is always positive. So, depending on the leading coefficient, the range could be (-∞,N) or (N,+∞) where N will be the absolute minimum of maximum of the ...
*July 3, 2015*

**math age problem**

Just translate the words to symbols: j-3 = (t-3)/2 j+3 = (m+3)/2 j = (m-3)/2 Unfortunately, those three equations do not determine their ages uniquely. Jim,Tom,Michael could be 4,5,11 5,7,13 6,9,15 . . . I suspect a typo in the problem.
*July 3, 2015*

**college geometry**

Since complementary angles add to 90°, x + (30+4x) = 90
*July 3, 2015*

**chemistry**

4.23 angstroms
*July 3, 2015*

**Physics**

surely your physics book discusses this. Do you expect a better explanation here? Try google and you will find many articles on these topics. Come on back if they don't clear things up. This forum is a great place to get help with specific problems, but general discussions...
*July 3, 2015*

**physics**

weight(force) = mg Ep = mgh work = force*distance You found the work, which is just ∆Ep work and energy are the same units.
*July 3, 2015*

**Math**

the maximum possible area would be a square, 75x75. But, since the length must be at least 80, make it as close to a square as possible. That would be 80x70
*July 2, 2015*

**Calculus Minimum**

y = xa^(1/x) y' = (1/x) a^(1/x) (x - ln(a)) Since the first two terms are never zero, y'=0 when x = ln(a)
*July 2, 2015*

**Algebra**

If there are a,b,c students studying exactly two of the subjects, taken in pairs, then (40+35+30)-(a+15 + b+15 + c+15)+15 = 70 a+b+c = 5 So, 5 students are taking exactly two of the subjects.
*July 2, 2015*

**Algebra**

you know that m = 2/3 p That can be written as 3m = 2p So, p = 3/2 m Or, knowing that (2/3)*(3/2) = 1 m = 2/3 p multiply both sides by 3/2 and you have 3/2 m = p
*July 2, 2015*

**Algebra**

3/2
*July 2, 2015*

**polynomials pankaj**

well, the product of the roots is (6a)/(a^2+a) = 1 6a = a^2+a a^2-5a = 0 a(a-5) = 0 a=5 30x^2+13x+30 has roots (-13±√3431 i)/60 which are reciprocals
*July 2, 2015*

**polynomials naman**

Just do the long division, and you see the remainder is (55-4k)/8 So, set that = -21 and solve for k.
*July 2, 2015*

**math**

3/7 * 3/6
*July 2, 2015*

**Algebra**

400(1+.05/12)^(12c) = 658.8 300(1+.06/4)^(4m) = 613.04 m-c = 2
*July 2, 2015*

**trigonometry26**

or, you can try it like this 1 + sin^2 Ø = 3sinØcosØ sin^2 Ø = (1-cos2Ø)/2 1 + (1-cos2Ø)/2 = 3/2 sin2Ø 3 - cos2Ø = 3sin2Ø 9 - 6cos2Ø + cos^2 2Ø = 9 - 9cos^2 2Ø 10cos^2 2Ø + 6cos2Ø...
*July 2, 2015*

**trigonometry 28**

It's just the Pythagorean Theorem in disguise.
*July 2, 2015*

**algebra**

since log(a)+log(b) = log(ab), you have log (x+8)(x-8) = 0 Since log(1) = 0, you have x^2-64 = 1 x^2 = 65 x = √65 why not also -√65?
*July 2, 2015*

**math**

it works because of the distributive property of multiplication and addition. 345 = 300+40+5 so, 345*245 = 5*245 + 40*245 + 300*245
*July 2, 2015*

**math**

powers of 7 end in 7,9,3,1,... so, 7^95 = 7^92 * 7^3 -- it ends in 3 do a similar thing for powers of 3. then do the subtraction.
*July 2, 2015*

**Math**

27x^3+8y^3 = (3x+2y)(9x^2-6xy+4y^2) (3x+2y)^2 = 144 = 9x^2+12xy+4y^2 . . .
*July 2, 2015*

**Math**

well, you have a triangle whose area is half that of the parallelogram. Use Heron's formula on it, since you have all three sides. Then double the result.
*July 2, 2015*

**Math - eh?**

evaluate a line that is there with two numbers? Not much to go on. What sort of problems are you studying just now? Are there no similar exercises worked out?
*July 1, 2015*

**calculus**

sounds true to me. So, what?
*July 1, 2015*

**Algebra - eh?**

there seems to be something missing from the first term. And your notation is inconsistent. log base{3} vs log_{3} Anyway, just recall that log a + log b = log ab regardless of the base.
*July 1, 2015*

**Math**

"none" is singular. There are 12 marbles in all, so P(red,red) = 3/12 * 2/11
*July 1, 2015*

**Calculus Derivative - ?**

where did you get d/dz e^z = z e^z?
*July 1, 2015*

**Calculus Derivative**

if y = u^v then y' = vu^(v-1)u' + lnu u^v v' Note that u^n and a^u are just special cases of this So, what you have is y= e^u y' = e^u u' u = x^x, so u' = x^x (1+lnx) y' = e^(x^x) x^x (1+lnx)
*July 1, 2015*

**math in distress**

Why are you adding teachers to students? If there are x teachers, x/1200 = 1/30 x=40
*July 1, 2015*

**math in distress**

since time = distance/speed, 480/(x+4) = 480/x - 1/2 x = 60 Why did you divide by 2? It's 480 miles each way. Amazingly, you got the correct answer! 480/60 = 8 480/64 = 7.5 That's like saying 16/64 = 1/4 because you can cancel the sixes!
*July 1, 2015*

**Math**

ac = b^(y/x) * b^(y/z) = b^2 That should get you started
*July 1, 2015*

**staTIStics**

9 balls in total P(white,red) = 6/9 * 2/8 PS That's color, not collar
*July 1, 2015*

**math in distress**

Why, Damon, I'm surprised! You never seem to miss a chance at poking fun at English units. And I (sort of) like all the strange units, just as I miss the old English coinage. That's weird, if the slug is defined in terms of pounds, and not the other way around. Guess ...
*July 1, 2015*

**mechanic**

recall that a cylinder of radius r and height h has volume v = πr^2 h so, that would be π*16*8 = 128π = 402 in^3
*July 1, 2015*

**physics**

momentum is mass * velocity So, two objects of different masses can have the same momentum if their velocities are different.
*July 1, 2015*

**physics**

you need a and b such that 12*15i + 36*5j = 12*6(.866i+.5j) + ai+bj 180i + 180j = 62.35ai+36bj a = 180/62.35 = 2.89 b = 180/36 = 5.00 So, the 36kg ball is moving with speed 5.78 m/s in the direction arctan(5/2.89)=60°
*July 1, 2015*

**Algebra**

17+10 = 27 total payment w/o coupon so, how much for each of the 4 people?
*July 1, 2015*

**calculus**

Not sure how to apply calculus to this. You can use the Rational Roots Theorem to narrow down your choices. That, and a little synthetic division turns up (5x-1)(x+3)(x^2-6x+13) Now you can find the complex roots.
*June 30, 2015*

**statistics**

This is discussed here: http://math.stackexchange.com/questions/353419/what-is-the-probability-that-either-a-or-b-but-not-both-will-occur
*June 30, 2015*

**science**

speed changes by 11m/s in 5s = 2.2 m/s^2
*June 30, 2015*

**Algebra 1**

Just list the f values for each x value. For example, f(-3) = -(-3)+4 = 7 so, 7 is in the range now do the others as needed. You already know that C and D are out.
*June 30, 2015*

**math**

geometric series. a = 1 r = -7/9 sum = 9/16
*June 30, 2015*

**math**

this is just a geometric series, with a = 1 r = -3/4 so, the sum is 4/7
*June 30, 2015*

**math**

n/(n+3) = 1 - 3/(n+3) The terms clearly converge to 1.
*June 30, 2015*

**Math**

I think I like (2/13)(5/12) Dang Siris!
*June 29, 2015*

**calc**

y' = x/y you can recognize that as an hyperbola x^2-y^2 = a^2 since (3,1) is on the curve, 9-1 = a^2 x^2-y^2 = 8
*June 29, 2015*

**math**

f'(t) = (t^2+11t+24)/(1+cos^2(t)) f'=0 when t^1+11t+24 = 0 That is, when t = -8 or -3 f"(t) = 2t+11 f"(-8) < 0, so the max is there.
*June 29, 2015*

**impoving writting via good speling**

I'll let others evaluate the style, but I can say right off that the grammar and spelling need some improvement. My corrections are in bold. There are awkward shifts between viewpoints (first, second, third person). ---------------------------------------- Email is quick; ...
*June 29, 2015*

**Cycle geometry**

or, using interior angles, 180(n-2) = 162n 180n-360 = 162n 18n = 360 n = 20
*June 29, 2015*

**math - eh?**

what does ^213 x mean? I know that x^2 means x squared I can't figure out what you're trying to express.
*June 29, 2015*

**math**

length is 4 less than 3 times the width less than means you're going to be subtracting. 6 is 2 less than 8 50 is 40 less than 90 So, expect to see "-4" because the length is 4 less than something. Less than what? 3 times the width. The "times" indicates...
*June 29, 2015*

**math**

kind doesn't really matter. Volume just depends on base and height.
*June 29, 2015*

**math**

3x-5y = 2000 2x-3y = 2000 x=4000 y=2000 So, A makes 12000 and spends 10000 B makes 8000 and spends 6000
*June 29, 2015*

**Physics**

a(t) = 6.60-2.29t v(t) = 6.60t - 1.145t^2 + c v(0) = 3.20, so c = 3.20, and v(t) = 3.20 + 6.60t - 1.145t^2 s(t) = 3.20t + 3.30t^2 - 0.3817t^3 + c s(0) = 7.30, so c = 7.30 s(t) = 7.30 + 3.20t + 3.30t^2 - 0.3817t^3 max speed occurs when a=0, or at t=2.882 v(2.882) = 12.7109 s(6....
*June 29, 2015*

**Nothern Cape collage**

We can assume the rock was thrown from a height of 0. So, now you know that h(t) = vt-5t^2 h(5) = 0, so 5v-125 = 0 v = 25 m/s
*June 29, 2015*

**calc**

why all the words? y = arcsin(x/4) using thin horizontal strips, the area is a = ∫[0,π/2] (4-x) dy But x = 4siny, so a = ∫[0,π/2] (4-4siny) dy = 2(π-2) You can check your work using vertical strips: a = ∫[0,4] y dx = ∫[0,4] arcsin(x/4) dx...
*June 29, 2015*

**Algebra**

since we want real coefficients, complex roots must come in conjugate pairs. So, f(x) = (x+5)(x-(2+i))(x-(2-i)) = x^3 + x^2 - 15x + 25
*June 29, 2015*

**Algebra**

From the first equation, you see that y = 5x+16 so, plug that into the 2nd equation and solve for y. Then you can figure out x.
*June 29, 2015*

**math**

The corners of the roughly triangular region are at (1,0),(0,2),(e^2,2) So, using thin washers of thickness dx, v = ∫[0,e^2] π(4^2-(2+lnx)^2) dx = 95.298 Using shells of thickness dy, we have v = ∫[0,2] 2π(2+y)(e^y-1) dy = 95.298
*June 29, 2015*

**Algebra**

f+r = 120 10f+13r = 12*120
*June 29, 2015*

**Algebra**

you are told that A + B = 50 39.95A + 30.34B = 1747.64 Now go for it.
*June 29, 2015*

**calc**

just review your text, and you will see why s(t) = 4 -10t + 15t^2
*June 29, 2015*

**math**

3x-4
*June 29, 2015*

**calculus**

correct.
*June 28, 2015*

**physics**

Looks good to me. except that v^2 = (240m/s)^2, not 240m/s^2, and g=10m/s^2, not ms^2 watch out fer them unit thingees.
*June 28, 2015*

**Math**

I'd say 12/15, right?
*June 28, 2015*

**Calculus Partial Fraction**

note that x^3-8 = (x-2)(x^2+2x+4) So, your fraction is now x^2 -------------------- (x-2)^2 (x^2+2x+4) As partial fractions, that becomes A/(x-2) + B(x-2)^2 + (Cx+D)/(x^2+2x+4) Placing all that over the common denominator, we have A(x-2)(x^2+2x+4) + B(x^2+2x+4) + (Cx+D)(x-2)^2...
*June 28, 2015*

**math**

You need to know how the DJIA is calculated, to figure the effect of any one stock.
*June 28, 2015*

**Math**

Using the given formula, your expression is correct, but its value is 3110.50 (D) Expressed correctly, of course, it would be 15,000(0.986975)^(10*12) You must have pushed some buttons wrong if you got (A). Or just guessed...
*June 28, 2015*

**Finance**

3000(0.9744^20) = 1785.94
*June 28, 2015*

**Calculus Partial Fraction**

well, clearly you can cancel x^2 and you are left with 1 / x(x-2) = A/x + B/(x-2) Now if you place the right side over the common denominator, you have (A(x-2)+Bx)/(x(x-2)) In order for the two numerators to be identical, you need (A+B)x-2A = 0x+1 That is, A+B=0 -2A=1 A = -1/2...
*June 28, 2015*

**Math**

could be any of those, depending on the proportion of Microsoft stock in the DJIA.
*June 28, 2015*

**Math**

Hmmm. 518400 = (10*9*8)^2 Why did you use that?
*June 28, 2015*

**Math**

assuming the order of choice does not matter, 6C4 * 6C4 or, 6C2 * 6C2 = 15*15 = 225
*June 28, 2015*

**Math**

P(red,red) = 3/5 * 2/4 You don't really need to record the color, since the bean was not replaced. Unless you have eaten it, you can just look at the two beans drawn.
*June 28, 2015*

**trigonometry**

If A is the angle of elevation of the sun, then tanA = height/shadowlength So, height/5 = 5/6 Looks like you need to review the basic trig functions. And always draw a diagram!
*June 28, 2015*

**Math**

Looks suspiciously like 30000. Just sayin' ...
*June 28, 2015*

**Maths Problem**

Dan finishes in 70 minutes, so Ellen finishes in 75 minutes. If Dan's speed is d m/min Ellen's speed is e m/min So, d = (15/14)e 35e = 35d-300 35e = 35(15e/14)-300 35e = 75e/2-300 5e/2 = 300 e = 120 So, the distance is 120*75 = 9000m You can check to make sure that the...
*June 28, 2015*

**math**

16x^2-24x-13=0 16(x^2 - 3/2 x) = 13 16(x^2 - 3/2 x + (3/4)^2 = 13+16(3/4)^2 16(x-3/4)^2 = 22 (x-3/4)^2 = 11/8 x = 3/4 ±√(11/8) or, x = (3±√22)/4 or, eschewing fractions, 16x^2-24x-13 = 0 16x^2-24x+9 = 13+9 (4x-3)^2 = 22 ...
*June 28, 2015*

**maths**

I don't believe that one side is only 60cm. Fix that, and just find twice the perimeter, then subtract twice the gate width.
*June 28, 2015*

**Math**

recall that 3^4 = 81
*June 27, 2015*

**Finite Math**

If there are x Daybrite sets and y Noglare sets, then you want to maximize p=425x+700y subject to x+y <= 400 x >= 70 y >= 160 a good tool is at http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html it will solve and graph the solution
*June 27, 2015*

**Geometry**

the two bases of a parallelogram are equal the two bases of a trapezoid are different Bh vs (b+B)h/2 These can only be the same if b=B.
*June 27, 2015*

**Math**

well, did you actually try the values to see which are or are not? (0,-1): -1 = 0^2-1? yes now you try the others and we can check your answers.
*June 27, 2015*