Wednesday

July 27, 2016
Total # Posts: 42,121

**math**

42p = 4-2p+8 44p = 12 ...
*June 3, 2016*

**science**

the resultant has magnitude √(23^2 + 41^2) and direction θ where tanθ = 23/41
*June 3, 2016*

**Discriminant**

(x-y)(x+y) = x^2-y^2 you have x = b y = √40 = 2√10 so, b^2-40 = (b+√40)(b-√40) = (b+2√10)(b-2√10)
*June 3, 2016*

**Alpha, beta**

no; fractions are perfectly acceptable. Most folks like to get rid of them, though, so the second form makes them more comfortable. You could just as well have used any of x^2/7 - 2x/7 + 11/63 = 0 5x^2 - 10x + 55/9 = 0 90x^2 - 180x + 110 = 0
*June 3, 2016*

**Chemistry**

how many on a single atom? Then multiply that by .002 * 6.023x10^23
*June 3, 2016*

**Algebra 1**

2x+4 <= 14 2x <= 10 x <= 5 so, 5 is the largest possible number. 2*5+4 = 14. Any number larger than 5 makes the expression more than 14.
*June 3, 2016*

**Math-Calc**

see earlier post
*June 2, 2016*

**Calc-Math**

If you don't even know where to begin, you must not have read the section on this topic. It says that the limit of f(x)/g(x) = f'(x)/g'(x) so, your limit is just (ln3 * 3^x - ln6 * 6^x)/1 = (ln3-ln6) = ln(3/6) = -ln2
*June 2, 2016*

**calculus**

without calculus, the distance from the point to the line is |4(-2)+2(-1)+5|/√(4^2+2^2) = √5/2 Using calculus, we have the distance z from (-2,-1) to (x,y) is z^2 = (x+2)^2 + (y+1)^2 But y = -(4x+5)/2, so z^2 = (x+2)^2 + ((-(4x+5)/2)+1)^2 z^2 = 5x^2 + 10x + 25/4 z...
*June 2, 2016*

**Geometry**

The x=15 is ok Not sure what the last set of values is for, but if they are for the 1st problem, no good. x^2 + (5-x)^2 = 25 x^2 + x^2-10x+25 = 25 2x^2-10x = 0 2x(x-5) = 0 x = 0 or x=5 So, the points of intersection are (0,5) and (5,0)
*June 2, 2016*

**Geometry**

well, y = 5-x, so x^2 + (5-x)^2 = 25 now just expand and solve the quadratic.
*June 2, 2016*

**Algebra**

x^3-5x^2+2x+8 ----------------- = x^2-3x-4 x-2
*June 2, 2016*

**Geometry**

right
*June 2, 2016*

**Geometry**

Assuming a typo, and you meant PN, we have PM/ZX = PN/ZY so, (x+5)/30 = (4x-10)/75 Now just solve for x.
*June 2, 2016*

**Calculus**

I just noticed that you did not specify that the y-axis formed part of the boundary. Without that condition, the horizontal strips extend leftward forever. Of course, you may have mixed up x and y in places, so ...
*June 2, 2016*

**Calculus**

This is most easily done by integrating on y, using horizontal strips. a = ∫[-1,3] x dy = ∫[-1,3] (8+2y-y^2) dy
*June 2, 2016*

**Math(Assignment due today)**

sounds like the ramp rises at a 4.7° angle, so it's ok.
*June 2, 2016*

**Pre-Calculus**

enter your coefficients at the url below to see all the details: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*June 2, 2016*

**Polynomials and properties of exponenets**

I get AC?BD
*June 2, 2016*

**Mathematics**

if the quiz is counted more than the other grades, things get more complicated. If the quiz counts as much as all the rest, then the final grade would be (88+95)/2 = 91.5 I suspect there is missing information here.
*June 2, 2016*

**Physics**

they both travel with the same speed. So, a longer wavelength means it oscillates more slowly. Recall that v = λf 3λ means f/3 to get the same v.
*June 2, 2016*

**Pre-Calculus**

next time, show your work, so we can find your error. From equation 1, x = 2y-5 plug that into #2, and you have x^2+y^2 = 25 (2y-5)^2 + y^2 = 25 5y^2 - 20y + 25 = 25 5y(y-4) = 0 y = 0 or 4 now you can find x values as needed, from either equation. http://www.wolframalpha.com/...
*June 2, 2016*

**Polynomials and properties of exponenets**

D,A,C,D Looks like some serious review is in order.
*June 2, 2016*

**Geometry**

Time to review the special angles: sin(30°) = 1/2 so, √sin(30°) = 1/√2 also, cos(30°) = √3/2
*June 2, 2016*

**algebra**

Reiny responded to this earlier, at http://www.jiskha.com/display.cgi?id=1464879381 If you want to pin it down more, there must be some other constraints.
*June 2, 2016*

**Pre-Calculus**

you got c correct, but did not express the coordinates of the foci. c = ±5 where is the center of the ellipse? Is the major axis horizontal or vertical?
*June 2, 2016*

**Math**

correct
*June 2, 2016*

**Pre-Calculus**

you are correct as far as you went, but recall that n*ln(x) = ln(x^n). 2lnx - 6lny + 1/3ln e^12 = ln(x^2) - ln(y^6) + (1/3)(12) = ln(x^2/y^6) + 4 = ln(e^4 x^2/y^6)
*June 2, 2016*

**5th Grade Math - Urgent Part II**

1,000,000 is the only number with prime factorization 2^6 * 5^6 = (2*5)^6 = 10^6 64 is 2^6 but has no factors of 5.
*June 2, 2016*

**Pre-Calculus**

your function is just a polynomial. The domain of all polynomials is (-∞,∞)
*June 2, 2016*

**algebra**

since distance = speed * time, 6x + 6(x-20) = 624
*June 2, 2016*

**MATH**

They gave you the functions. Did you graph them as suggested? Here are the lines: http://www.wolframalpha.com/input/?i=plot+y%3D25%2B10x+,+y+%3D+18%2B15x Now you can surely answer the questions.
*June 2, 2016*

**Trigonometery**

no one is assigned to sit here and watch for problems. We have lives, too, and when we get a chance, we check in. As you know, the function a sin(kx) has amplitude a and period 2pi/k, so you can use your requirements to produce the function -4sin(8x) But you probably figured ...
*June 2, 2016*

**match**

apparently you have knowledge about ditches and absorption rates which you have not shared here.
*June 2, 2016*

**Calculus**

So, each square has base and height e^-x Thus, the volume, adding up all those thin squares, is ∫[0,2] (e^-x)^2 dx = ∫[0,2] e^(-2x) dx let u = 2x, and that becomes (1/2)∫[0,4] e^-u du ...
*June 2, 2016*

**Physics**

wrong
*June 2, 2016*

**math**

(1+r)^12 = 2 r = 2^(1/12)-1
*June 2, 2016*

**Math**

I assume you really meant 1/(x-1)+1/(x+1) ------------------ 1/(x-1)-1/(x+1) cross-multiply to put top and bottom over a common denominator of (x-1)(x+1) Then since the same denominator occurs top and bottom, it can be discarded, just as (2/3)/(5/3) = 2/5 now you have (x+1)+(x...
*June 2, 2016*

**Math**

gibberish
*June 2, 2016*

**Maths**

kx^2-5x+k is not a cubic polynomial.
*June 2, 2016*

**physics**

Since F=ma, the acceleration of the car is 1/5 gravity. So, how long does it take the car to move 20cm, under (1/5)g acceleration? s = 1/2 at^2
*June 2, 2016*

**Math Please Help Quick**

.20 * 20 = ?
*June 2, 2016*

**math**

t+r = 800 (3/4)t + (5/6)r = 800-192 to find r, substitute for t: (3/4)(800-r) + (5/6)r = 608 (1/12)r + 600 = 608 r/12 = 8 r = 96
*June 2, 2016*

**math**

if you google manual cube roots, you will find several nice explanations of how to extract roots by hand. It's not worth the effort, since calculators are so handy these days. Use your calculator to evaluate 36.13^(1/3) power
*June 2, 2016*

**maths**

draw a diagram. review your basic trig functions. Now it is clear that 2.5/x = cos60° now just solve for x, the length of the ladder.
*June 2, 2016*

**Math Year 10 - Simultaneous equations**

c = 2s 2c+4s=104 now solve for c
*June 2, 2016*

**Mathematics**

It'd be nice to have some of your work to look at, eh? 3/x + 5/y = 4 9/x + 4/y = 5 It gets messy to try and solve for x or y, so solve for 1/x instead. 1/y = (4-3/x)/5 thus, 9/x + 4/5 (4-3/x) = 5 45/x + 16 - 12/x = 25 33/x = 9 1/x = 9/33 = 3/11 so, x = 11/3 now plug in to ...
*June 2, 2016*

**Figurs and Numbers**

12% = 0.12 spending means that amount is subtracted. So, subtract .12 twice. Having done that, subtract another 25% = 0.25, and the remainder is 2010. Then find x, the original amount which leaves that remaining amount. Finally, knowing x, 25% of 57% of that amount is what was...
*June 2, 2016*

**Figurs and Numbers**

x(1-.12-.12)(1-.25) = 2010 .76*.75x = 2010 x = 3526.32 x * .76 * .25 = $670.00 on education
*June 2, 2016*

**Pre-Calculus**

well, it could be (x+1)(x-7)(x^2-2) = what you wrote. extra credit: are there any others?
*June 2, 2016*

**Geometry**

I agree. It looks like a syllogism, but there are too many things wrong.
*June 2, 2016*

**Sxiences**

recall that F = ma now just plug in your numbers to get m.
*June 1, 2016*

**Spanish**

correct
*June 1, 2016*

**MAth**

simple interest: 200*.06*2
*June 1, 2016*

**Chemistry**

depreciation
*June 1, 2016*

**Chemistry**

two errors, DrRebel: (0.693/3.8) ≠ 0.8663 it was 98.4, not 94.4
*June 1, 2016*

**Chemistry**

98.4 * (1/2)^(19/3.8) = 3.075 g
*June 1, 2016*

**Mathematics**

for the perimeter, since p = 2(length+width) p is even, since it is a multiple of 2.
*June 1, 2016*

**Algebra**

How much more is 9 than 7? You do it by finding the difference: 9-7 so, do this the same way: (9x+8)-(5x+6) ...
*June 1, 2016*

**math**

divide that by 2, since it takes two hands to shake once.
*June 1, 2016*

**Math**

x:9=2/3:36 x*36 = 9 * 2/3 36x = 6 x = 1/6 = 0.1666 or, x/9 = (2/3)/36 x/9 = 2/108 x/9 = 1/54 x = 9/54 = 1/6 maybe you should try some other proportions with less complicated numbers, to learn the method and why it works.
*June 1, 2016*

**Math**

you have to subtract the width of the frame, both top and bottom. The remaining height is occupied by the picture 5 2/3 * 2 = 10 4/3 = 11 1/3 now subtract that from the overall height, and you have 25 5/6 - 11 1/3 = 25 5/6 - 11 2/6 = 25-11 + 5/6 - 2/6 = 14 3/6 = 14 1/2
*June 1, 2016*

**Science - Chemistry**

Kind of depends on the size of the diamond, wouldn't you say?
*June 1, 2016*

**Math please help**

note that as x grows by 2, y falls by 1. That gives you a slope of -1/2. So, start with y = -1/2 x But, if you plug in x=2, that gives y = -1/2 (2) = -1 But in fact, y=1. So you need to add 2, giving you y = -1/2 x + 2 or, y = (4-x)/2 Use the other values of x and y to see ...
*June 1, 2016*

**Pre-Cal: Plz help!**

Go to Reiny's url and tweak the input until it agrees with what you intended. It's probably just a combination of typos.
*June 1, 2016*

**math**

me either, but recall that 1L = 1000cm^3, so find your volume in cm^3 and divide by 1000
*June 1, 2016*

**Pre-Cal**

The answer makes me think you are trying to find the derivative of ∛(x^2+3)/x = ∛(x^2+3) * x^-1 That would be ∛(x^2+3)*(-1)(x^-2) + (1/3)(x^2+3)^(-2/3) * (2x)(1/x) To put all that over (x^2+3)^(2/3), multiply the first term, and you get (x^2+3)(-1/x^2) + (1/3...
*June 1, 2016*

**MATH**

clearly, E=T+1 because of the carry. So, T is 1,5,6 G is even (since it is N+N), so it is 2,6 Now just a little trial and error yields 671 +51 ------ 722
*June 1, 2016*

**MATH**

If you were not given letters for the answer, then just pick any values you want!
*June 1, 2016*

**algebra**

so, even though Bosnian started out with a yes his work shows that the answer was D, not A.
*June 1, 2016*

**Algebra**

can you not plot the points and draw a curve through them? Note that as x grows by 1, y drops by 1/2 of its value. So, it looks like y = 10 * 2^-x an exponential curve.
*June 1, 2016*

**Pre-Calculus**

vertical asymptotes occur where the denominator is zero and the numerator is not. So, your graph has a vertical asymptote at x=0 try entering your function at wolframalpha.com to see its graph, and other information. Note that as long as x≠4, f(x) = 1/x There is a hole ...
*June 1, 2016*

**Physics**

since time = distance/speed, 50/75 + x/45 = 9/4 You live 50+x miles away.
*June 1, 2016*

**math**

since (10^-8)^3 = 10^-24,that would be ∛36.31 * 10^-8
*June 1, 2016*

**math**

just solve the inequalities to see which has the smallest solution. remember that for fractions, a larger denominator means a smaller quotient. So, for example, if w>4, w+2 > 6, so 4/(w+2) < 4/6 = 2/3 reason similarly for the others.
*June 1, 2016*

**Math help plz??**

time = distance/speed, so 3.54x10^7 / 3x10^8 = 1.18x10^-1 or, 0.118 seconds
*June 1, 2016*

**math**

you can play around with this stuff at http://davidmlane.com/hyperstat/z_table.html
*June 1, 2016*

**Maths**

(x+y)/2 = 7 xy/3 = 16 y=48/x x+48/x = 14 x^2-14x+48 = 0 (x-6)(x-8) = 0 x and y are 6 and 8
*June 1, 2016*

**Polynomials**

mine, too.
*June 1, 2016*

**maths**

or, you could just solve the two equations using the quadratic formula. That would yield x = [3y±√(5y^2-4)]/2 x = [y±√(152-35y^2)]/6 equate those two and you get y=±2
*June 1, 2016*

**maths**

I am assuming you want to solve the system of equations x^2-3xy+y^2+1 = 0 3x^2-xy+3y^2 = 13 from the second, we have xy = 3x^2+3y^2-13 using that in the first, we have x^2-3(3x^2+3y^2-13)+y^2+1 = 0 x^2-9x^2-9y^2+39+y^2+1 = 0 -8x^2 - 8y^2 = -40 x^2 + y^2 = 5 Using that in ...
*June 1, 2016*

**math plz help ;-;**

these two make substitution the method of choice. x+y=2 means y = 2-x So, using that in the other equation, 2x-(2-x) = 10 2x-2+x = 10 3x = 12 x = 4 now use either equation to see that y = -2 check: 2*4-(-2) = 8+2 = 10 4+(-2) = 4-2 = 2 similarly, you can substitute for x: x = 2...
*June 1, 2016*

**Precalculs**

regardless of the base, log(1) = 0, because x^0 = 1 so, what you have is 6x-12 = 0 x = 2 try writing log_x(n) for log of n (base x). The underscore indicates the base.
*June 1, 2016*

**Math-Calc**

you could write f(x) = 7*ln(x^2+5)^-1 then, using the power and chain rules, f'(x) = 7*(-1)*ln(x^2+5)^-2 * (2x) = -14x/ln(x^2+5)^2 f'(1) = -14/(ln6)^2
*June 1, 2016*

**Radicals3**

x√(12x^4) = x√(4x^4*3) = x(2x^2)√3 = 2x^3√3 3x√x^2 * 2√x^5 = 6x√(x^2*x^5) = 6x√(x^6 * x) = 6x*x^3 √x = 6x^4 √x -7 = 2-√(12x-3) -9 = -√(12x-3) 81 = 12x-3 84 = 12x x = 7
*May 31, 2016*

**Radicals2**

9√72 / 2√24 = 9√(3*24) / 2√24 = 9√3√24 / 2√24 = 9√3/2
*May 31, 2016*

**Radicals**

∛-192 = ∛(-1*64*3) = -1*4*∛3 -6∛13) = ∛((-6)^3*13) = ∛(-216)(13) = ∛-2808
*May 31, 2016*

**math plz check ;-; sorry**

by definition, (√47)^2 = 47 just as √2 * √2 = 2 (√x)^2 = x That is the definition of the square root of x: the number which, when squared, produces x.
*May 31, 2016*

**math plz check ;-; sorry**

so, you're saying that 47 > 50 ?
*May 31, 2016*

**math**

one way is just to compute the equations of the lines joining the pairs of points, and show that they intersect in the same point. On the unit circle, let P1 = (1,0) P2 = (cos pi/9,sin pi/9) ...
*May 31, 2016*

**Math**

In your equation, p and q are vectors so, find where the y-component is zero.
*May 31, 2016*

**math plz check ;-;**

so, you're saying that 47 > 50 ?
*May 31, 2016*

**Algebra**

first step: lose the mixed numbers! 5/6-2(-1 3/4)/5 1/5 = 5/6-2(-7/4)/(26/5) = (5/6) + (14/4)*(5/26) = 5/6 + 35/52 = 235/156
*May 31, 2016*

**tripz**

This kind of thing is what log tables were used for. Now we have calculators.
*May 31, 2016*

**Statistics**

you can find this and other cool answers at http://davidmlane.com/hyperstat/z_table.html
*May 31, 2016*

**Math**

He has 9*68=612 points so far He needs 10*70=700 points to achieve his desired average So, haw many more points does he need?
*May 31, 2016*

**Math(Reiny Please Help)**

is there something unclear about the solution at http://www.jiskha.com/display.cgi?id=1464662427 ??
*May 31, 2016*

**Math**

(4x^2 - 2x-1) - (-3x^3 + 2) 4x^2 - 2x - 1 + 3x^2 - 2 7x^2 - 2x - 3
*May 31, 2016*

**physics**

solve for t in 0.5 - 0.05t = 0
*May 31, 2016*

**Trignometry**

maybe you can fix the problem. As it stands, you have mixed up a trig function and the angle: tan(theta+alpha) + 2alpha
*May 31, 2016*