Thursday

August 25, 2016
Total # Posts: 42,758

**Java programming**

I'm sure you can do the I/O. The calculation is v = Math.PI * r*r * h a = 2*Math.PI * r * (r+h) or, for r-squared, there's always Math.pow(r,2)
*August 13, 2016*

**Maths**

(1) 16(1 - 1/2^10)/(1 - 1/2) (2) 1/9 (3^8 - 1)/(3-1) see how these match up with your general formula.
*August 13, 2016*

**math**

6250(1 + r/4)^2 = 6760
*August 13, 2016*

**physics**

Since 100°C = 60°M, the C degrees are 3/5 as big as the M degrees. so, C = 3/5 (M-20) + 0
*August 13, 2016*

**science**

it is where all motion stops. It can never be achieved, due to the Heisenberg Uncertainty Principle. But, we've gotten mighty close: 0.0025°K 0°K = -273.15°C 0°R = -459.67°F
*August 13, 2016*

**Math**

just solve for t in -16t^2+86t+212 = 320
*August 13, 2016*

**Math**

7x + x^2 = -12
*August 13, 2016*

**math**

3x-6 = 66
*August 13, 2016*

**geometry**

(11+2w)(6+2w) - 11*6 = 28 now just solve for w
*August 13, 2016*

**math**

since primes must end in 1,3,7,9 there are only a few decades to check.
*August 13, 2016*

**math**

If the mug holds x ml, then x/2 + 25 = 3x/5 Now just solve for x
*August 13, 2016*

**Pre-Calculus**

since sec^2Θ = 1+tan^2Θ yes, up to the sign. secΘ might be plus or minus for a given value of tanΘ.
*August 12, 2016*

**Algebra**

h(x) = 2x^2-7x the average rate of change is just the slope of the line from (1,h(1)) to (5,h(5)). That is, (h(5)-h(1))/(5-1)
*August 12, 2016*

**Maths**

multiply top and bottom by 1+sin+cos For ease of reading, I'll just use s and c for sinx and cosx (1+s+c)/(1+s-c) * (1+s+c)/(1+s+c) = (1+s+c)^2 / ((1+s)^2 - c^2) = (1+s^2+c^2+2s+2c+2sc) / (1+2s+s^2-c^2) = (2+2s+2c+2sc)/(1+2s+s^2-1+s^2) = (2+2s+2c+2sc)/(2s+2s^2) = ((1+c)(1+...
*August 12, 2016*

**Math**

well, |-8| = +8 so, what do you think?
*August 12, 2016*

**Algebra**

your copy/paste is running into some font problems. My browser does not properly display ¨C or ¡Ù I'm guessing they are - and ≠ If I'm right, then The opposite of -4 is 4 (though "opposite" is a rather vague mathematical term) The ...
*August 12, 2016*

**math**

perimeter can be irrational and area rational, since the nonzero sum of two irrationals is irrational the product of two irrationals may be rational √5 * √5 = 5
*August 12, 2016*

**Stats**

since the draws are independent, just multiply their probabilities: 3/9 * 2/8
*August 12, 2016*

**math My Bad^2**

Sorry, Bosnian. Blew that, too.
*August 12, 2016*

**math - MyBad**

Damon has it right What was I thinking???
*August 12, 2016*

**math**

Look at the table. x changes by +2 y changes by -1 The slope is the ratio of changes, y-change / x-change = -1/2 So, the answer is g if there is a typo and it reads -1/2
*August 12, 2016*

**algebra 2**

trick answer! Nice one.
*August 12, 2016*

**math**

90/(7+8) = 90/15
*August 12, 2016*

**math**

after 28, there were 14 below 3 and 14 above 2. So, what do you think? Check the last two throws. 30*3 = 90 The sum of 28 throws was 78, so the last two had to add up to 12.
*August 12, 2016*

**precal**

moving right along, you know that the parabola x^2 = 4py has focus at (0,p). You have (x-3)^2 = -5(y+5) So, 4p = -5 and the focus is at (0,-5/4) but shifted by (3,-5) to (3,-25/4) as Reiny's graph shows.
*August 11, 2016*

**Geometry**

much better.
*August 11, 2016*

**Geometry**

I like C more. When the final arrives, he'll do better if he has reviewed and learned his previous material. D is just wishful thinking.
*August 11, 2016*

**Math**

4000(1 + .048/12)^(12*9) I'm sure your book has the formula A(1+r)^t you have to adjust it if the rate is compounded more than once per year. If monthly, then n=12 times per year. Thus, the monthly interest is 1/12 the annual rate, and there are 12 times as many ...
*August 11, 2016*

**Calculus**

see the related questions below. Solutions are provided, just using different values. If you get stuck, come on back with what you have so far. Try this one: http://www.jiskha.com/display.cgi?id=1226871282
*August 11, 2016*

**Math**

to get the graph, just graph them... To find where the graphs intersect, solve algebraically y^2-2x+2=0 and x-y-5=0 x=y+5, so y^2-2(y+5)+2 = 0 y^2-2y-8 = 0 (y-4)(y+2) = 0 Now you know y, so you can get the corresponding x values. 2x^2+3y^2=21 3x^2-4y^2=23 8x^2+12y^2 = 84 9x^2-...
*August 11, 2016*

**Algebra simplifying fractions**

5y(2y-1) / 5y = ?
*August 11, 2016*

**Algebra**

(m^2+mn)/(m^2-mn) = m(m+n) / m(m-n) = (m+n)/(m-n)
*August 11, 2016*

**math**

x + 2/3 x = 180
*August 11, 2016*

**Vector , physics**

by symmetry, it is clear that AB+AF = k1*AO AC+AE = k2*AO AD = 2AO Now you should be able to show that k1+k2 = 4
*August 11, 2016*

**jangid**

without going through all the algebra, recall that 120 = 5! = 1*2*3*4*5 That help?
*August 11, 2016*

**Math**

geez, 11 minutes? impatient much?
*August 11, 2016*

**Math**

If there are n cards, then n is a multiple of 2. so, you want an even number which is 3a+2 or 5b+1 a must be even and b must be odd. 26 = 3*8+2 = 5*5+1 = 2*13
*August 11, 2016*

**Calculus**

yes, those are the two values in the interval [0,2pi)
*August 11, 2016*

**Algebra**

3x5+4-2x2+6-4=15 since the only two odd numbers are the 3x5, and only the product of two odds or the sum of an even and an odd is odd, we must have either 3x(5...) or (3x5)+... see what you can do with that
*August 11, 2016*

**Probability**

well, 19 of the 20 stamps have some blue or red, right?
*August 11, 2016*

**math**

The 1st number is larger than the 2nd: a/b = (5/6):(2/3) = 5/4 So, a = 5/4 b = b * 1.25 so, a is 25% larger than b
*August 10, 2016*

**Sum of geometric sequences**

a=5 r=3 S10 = a(r^10-1)/(r-1) plug and chug
*August 10, 2016*

**Calculus**

better use implicit differentiation: e^(xy) = sinx e^(xy)(y + xy') = cosx x e^(xy) y' = cosx - y e^(xy) y' = (cosx - y e^(xy))/(x e^(xy)) but e^(xy) = sinx, so y' = (cosx - y*sinx)/(x*sinx) y' = (cotx - y)/x or, using logs, e^(xy) = sinx xy = ln(sinx) y + ...
*August 10, 2016*

**Calculus 1**

try using the binomial expansion. You will see that the expression is e^(6/x)^(x/2) + (x/2)e^(6/x)^(x/2-1)(8x) + ... = e^3 + 4x^2*e^3/e^(6/x) + ... where all the rest of the terms ->0 so, the limit is e^3
*August 10, 2016*

**Calculus**

surely you can find the derivative of both top and bottom, no?
*August 10, 2016*

**science**

clearly, that would be 400N/cm^2
*August 10, 2016*

**MATH**

what sentence? All I see is an expression.
*August 10, 2016*

**Geometry**

15 seconds * 5rpm = 5/4 rev So, after 15 seconds, it has rotated 1 1/4 times. I am also having trouble getting the given matrix. How does it rotate? What is the axis of rotation?
*August 10, 2016*

**Chemistry**

since 1mL = 1 cm^3, 16.3 cm^3 * 10.5g/cm^3 = 16.3*10.5 g
*August 10, 2016*

**Chemistry**

use the density of Al to find the volume occupied by 54g g ÷ gm/cm^3 = cm^3
*August 10, 2016*

**Pre-Calc**

There are no intervals involved. since sin(π/4) = 1/√2 the principal value of arcsin, Sin^-1(1/√2) = π/4 But, since there are many other angles, sin^-1(1/√2) = π/4 or 3π/4 and since the period of sin(x) is 2π, sin^-1(1/√2) = &#...
*August 10, 2016*

**Math**

If you mean scale factor, then you multiply whatever dimensions you have by the scale factor.
*August 10, 2016*

**algebra**

12/2 (2a+11d) = 168 a+6d = 7 Now just solve for a and d.
*August 10, 2016*

**Math**

try 500x > 5280 or, x > 5280/500
*August 10, 2016*

**math**

minor sector: a = 1/2 r^2 θ = 1/2 * 25 * π/3 = 25/6 π no idea where A and B are, but angles do not have areas. minor segment: 1/2 r^2 (θ-sinθ) = 1/2 * 25 (π/3 - √3/2) arc length = rθ = 5 * π/3 = 5/3 π I see you found the area ...
*August 10, 2016*

**Maths**

in English, there are no ands in writing large numbers. So, four hundred one thousand eight hundred nine = 401,809
*August 10, 2016*

**History**

thank you
*August 10, 2016*

**History**

Many changes occurred to the a freedman's life during reconstruction. Which of the following freedoms did these individuals gain? 1- right to legalize a marriage and raise a family 2- freedom to choose where to live 3- freedom to establish churches and community centers 4...
*August 10, 2016*

**Math**

compare the unit prices: $5.99/2L = $2.995/L and $2.95/.75L = ? $/L
*August 10, 2016*

**math**

100-(80+85-73) = 8
*August 10, 2016*

**probability statistics**

For A and B, just divide the number of your color by the total. For example, P(blue) = 7/20 D is a trick question.
*August 10, 2016*

**algebra**

ok - what is the cost? did you use an editor?
*August 10, 2016*

**algebra - typo**

what does ^0.3x mean? should there be an x^2 in there somewhere? or just .03x ?
*August 10, 2016*

**math**

Efa started out right, but then lost track of the math. 100% is 10 times 10% So, the full tank is 10 times 30L = 300L
*August 10, 2016*

**physics**

PV=k so, P*8 = 48*15
*August 10, 2016*

**Math**

7 days @ 6 per day is 42 eggs for the week. So, add up the rest and see how many were needed to get to 42.
*August 10, 2016*

**chemistry**

well, you can start off with 2NH3 = N2 + 3H2 now start by changing moles
*August 10, 2016*

**Discrete Mathematics and its Application**

By "truth" do you mean a truth table? If so, just list the 8 rows and the 8 values of the functions, and it is easy to show which are equivalent.
*August 9, 2016*

**Math**

In terms of cm, 57m 50cm = 5750cm 22m = 2200cm The greatest common factor can be found using 5750 = 2 * 5^3 * 23 2200 = 2^3 * 5^2 * 11 So, the GCF is 2*5^2 = 50 Using 50cm stones, the courtyard is 115x44 = 5060 stones
*August 9, 2016*

**math**

huh? None of the above. The total marks for the 10 students is 10*8 = 80 I suspect you have left out something, like the size of the group.
*August 9, 2016*

**Reposting question- Pre-calc**

Excuse me?? Can you not just plug in the x-value? y = 5cot(-2x) so, at x = π/6, y = 5cot(-2 * π/6) = 5cot(-π/3) = -5cot(π/3) = -5/√3
*August 9, 2016*

**Maths**

See the related questions below. A good one is http://www.jiskha.com/display.cgi?id=1353315962 not quite yours, but very close.
*August 9, 2016*

**Mathematics**

In English, I think this reads A parking lot has a capacity of 75 cars. If 3/5 of it is full at one time, how many more cars can be parked? Well, 3/5 of 75 is 45, so what do you think?
*August 9, 2016*

**Maths**

google cylinder inscribed in cone and you will find may expositions of a cylinder inscribed in a cone of base radius R and height h. The only twist to your problem is that you have h and α instead of h and R. If you draw a side view, it its clear that R/h = tan α Now...
*August 9, 2016*

**Math**

e^(.09t) = 2 now solve for t years
*August 9, 2016*

**Math**

5 * 12.3 = 61.5 That is the total of the 5 numbers with that average. So, the missing number is 61.5 minus the sum of the first 4 numbers.
*August 9, 2016*

**math**

497
*August 9, 2016*

**math**

One thousand people stood in a very large circle. Each starting with the Jennifer Lopez look alike, wore a sign on his or her back with a numeral from 1 to 1000 in a clockwise sequence. They began counting off. The Jennifer Lopez look alike said one in and remained in the ...
*August 9, 2016*

**ap chemistry**

(3 mole N)/(1 mole Al(NO3)3) * (.75 mole Al(NO3)3)/L * 0.40L = (0.9 mole N)
*August 9, 2016*

**Science**

(3x)^2 + (5x)^2 - 2(3x)(5x)cos120° = 28 9x^2 + 25x^2 +15x^2 = 28^2 x = 4 So, the two forces are 12 and 20 check: <12,0> + <10,10√3> = <22,10√3> magnitude is 28
*August 9, 2016*

**Mathematics**

If you mean (1+ax)/(1-ax) = p/q q(1+ax) = p(1-ax) q + aqx = p - apx aqx+apx = p-q x(ap+aq) = p-q x = (p-q) / a(p+q)
*August 9, 2016*

**science**

think of a weight w on a horizontal plane (θ=0). All of the force is downward. That means that perpendicular is w*cosθ parallel is w*sinθ As the board is tilted, less and less is perpendicular, and more and more is parallel
*August 9, 2016*

**Statistic**

the possibilities are, of course, 0R 6W 1R 5W 2R 4W So, can you determine how many ways for each of those setups?
*August 8, 2016*

**Calc - help needed**

You did not read the domain carefully, nor did your points meet the requirements. All of your points are in QII and QIV, where tan(x) = -1/√3 The domain is [-3π/2,2π], and all of your points must lie in QI or QIII, where tan(x) > 0 That would mean that the x...
*August 8, 2016*

**Algebra Quadratic Functions**

as usual, the vertex is at s = -b/2a = 3/2 y(3/2) = 25/4 so far, so good. So, when does it hit the ground? When y=0, naturally. So, -s^2+3s+4 = 0 (s+1)(4-s) = 0 so, it hits the ground after 4 seconds.
*August 8, 2016*

**statistics**

Just as the median is the middle point in the range, the 1st quartile is the middle point in the lower half. Your data set is so small that it's hard to divide equally. But, the url below discusses it in some detail. https://en.wikipedia.org/wiki/Quartile
*August 8, 2016*

**math quadratic functions**

If x is one side, let y be the other. Then 4x+4y = 40 x+y = 10 y = 10-x The total area is thus a = x^2+y^2 = x^2 + (10-x)^2 = 2x^2-20x+100 a has a minimum at x = 20/4 = 5 As expected, minimum area occurs when the two squares are in fact equal.
*August 8, 2016*

**Algebra Quadratic EFuncyoon**

the maximum area is at the vertex of the parabola. That is always at the axis of symmetry, x = -b/2a In this case, that is at x = 100/4 = 25 2*25^2 - 100*25 = -1250 ??? Your function cannot be correct, since it is a parabola opening upward, and thus has no maximum. The ...
*August 8, 2016*

**Math**

6n+7p = 2170 If he had x cents left, then 7n+7p = 2170+x+30 6n+8p = 2170+x-50 x = 180 n = 210 p = 130 So, a notebook costs $2.10
*August 8, 2016*

**Calculas**

well, the slope is 3/4 so plug that into the other forms. y = 3/4 x + ? y-k = 3/4 (x-h)
*August 8, 2016*

**Math**

28-6n+7(5n-2)-2n 28-6n+35n-14-2n ...
*August 8, 2016*

**Math**

no, -130-48 = -178 if you think the other way around, the depth started at 130 and then was reduced by 48 as the penguin rose 130-48 = 82 or, as feet from the surface, -130+48 = -82 Get out your number line, and remember that negative means go left, and positive means go right...
*August 8, 2016*

**Math**

-130 + 48 = ?
*August 8, 2016*

**How's that again?**

you want to reword that so it makes sense?
*August 8, 2016*

**Math**

Nope. It's 8^-3, or 1/8^3 B
*August 8, 2016*

**Maths B**

.75m/s * 60s = 45m Draw a diagram. It will show that y cot 30° - y cot 50° = 45
*August 8, 2016*

**Mathematics**

7(x+4) - 2/3 (x-6) < 2(x-3(x + 5)) 7x+28 - 2/3 x + 4 < 2x - 6x - 30 19/3 x + 32 < -4x - 30 31/3 x < -62 x < -6
*August 8, 2016*

**precal**

I assume you mean 2sin2x - 2cosx = 0 4sinx cosx - 2cosx = 0 2cosx(2sinx-1) = 0 so, cosx = 0 or sinx = 1/2 so, there will be four solutions in [0,2π)
*August 8, 2016*

**Physics - eh?**

how can you have a depth of 10 meters per second ???
*August 8, 2016*