Thursday
August 27, 2015

Posts by STEVE


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

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