Tuesday

June 28, 2016
Total # Posts: 41,490

**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*

**Math**

the area of a circle with radius 15 is pi r^2 = 225pi
*May 31, 2016*

**math**

that would be 3(2y) + 1(y+3) = 6y+y+3 = 7y+3
*May 31, 2016*

**math plz help ;-;**

the equation of your line is y-8 = -3(x+4) Now massage that to see which choice it matches.
*May 31, 2016*

**math plz help ;-;**

plug in the points for your equation: (-4,8): -3(8) = -4-4 -24 = -8 BZZZT! Try again (1,-7): -3(-7) = 1-4 21 = -3 BZZZT! Not that one either.
*May 31, 2016*

**Physics**

start: a = v/t = 36km/hr/10s = 3.6 km/hr/s you can convert km/hr to m/s if you desire the usual m/s^2 value. to stop takes twice as long, so a = 1/2 as much.
*May 31, 2016*

**maths**

x+y = 14 1/x + 1/y = 7/20 Now just crank it out.
*May 31, 2016*

**maths**

3/7 * 3/7
*May 31, 2016*

**Math**

42
*May 31, 2016*

**math plz check ;-;**

none of those choices matches the equation. It can be written as -3y = 12-2x or y = 2/3 x - 4 And of course, no graphs are shown here...
*May 31, 2016*

**Algebra 1**

since distance = speed * time, 7(x+60) = 9(x-60)
*May 30, 2016*

**Math**

35000 * (1.05^40-1)/(1.05-1)
*May 30, 2016*

**math**

well, he has to make 9 cuts, so 9*10
*May 30, 2016*

**Math2**

I assume the bowl is circular, with a parabolic cross-section. If we let the vertex be at (0,0) then we have y = kx^2 where y(15) = 9 so, y = 1/25 x^2
*May 30, 2016*

**Math1**

it hits the ground when h=0. So, just solve -12(t+2)^2 + 120(t+2) = 0 or, if you prefer t^2-6t-16 = 0
*May 30, 2016*

**Math (Calculus)**

The slope at any point (x,y) is dy/dx = (dy/dt)/(dx/dt) = (2t+1)/(2t) We want to find t such that the tangent line is y=kx (that is, it passes through the origin). At that point y = kx, so k = (t^2+t)/(t^2+3) That means that we need the slope = k, or (2t+1)/(2t) = (t^2+t)/(t^2...
*May 30, 2016*

**Algebra**

we want x,y and k such that (x+k)(y+k) = 2xy xy+kx+ky+k^2 = 2xy y = k(x+k)/(x-k) So, there are lots of solutions, with varying dimensions. x y k xy (x+k)(y+k) 2 3 1 6 12 3 10 2 30 60 and so on
*May 30, 2016*

**Math - volume about y axis**

The region is bounded above by the x-axis. That is, it is the region below the axis. Since it is symmetric about the y-axis, we really only need to rotate the region from 0 to 1. So, using discs, v = ∫[0,1] πr^2 dy where r = x, so r^2 = x^2 = y+1 v = ∫[0,1] &#...
*May 30, 2016*

**Algebra**

arrange the scores in order. The 80th %ile is that score above 80% of the others. Your score is the 78th %ile, so it should be close to the score found above.
*May 30, 2016*

**math plz help ;-;**

-2(x-3)+4=8x-20 lose the parentheses: -2x+6+4=8x-20 move all the x stuff to the left, and the numbers to the right: -2x-8x = -20-6-4 simplify each sides: -10x = -30 divide by -10 to get x alone: x = 3 check that it fits the original equation: -2(3-3)+4=8*3-20 0+4 = 24-20 yep
*May 30, 2016*

**math @**

finally discovered the difference between () and ||, eh, Stefan?
*May 30, 2016*

**Math**

L+K=900 L=K+400
*May 30, 2016*

**algebra**

Since the tax is only on the dress, I'd say 10.50 + 12.00*1.09
*May 30, 2016*

**algebra 1**

Have you talked to "Ann"? http://www.jiskha.com/display.cgi?id=1464626459
*May 30, 2016*

**Math**

This is strange. D(0) = 21 D(8) = 9 D(14) = 0 I am having a hard time relating T values with travel time. Does he server the ball at T=0? Can't be, since then he is 21 ft from the ball. The distance is always decreasing, so clearly the equation describes the return trip ...
*May 30, 2016*

**Math**

Draw a diagram. The measures of the angles of triangle PQR are P:43 Q:83 r:54 Now just use the law of sines to get PR: PR/sin83 = 10/sin54
*May 30, 2016*

**Maths**

Draw a diagram. The measures of the angles of triangle PQR are P:43 Q:83 r:54 Now just use the law of sines to get PR: PR/sin83 = 10/sin54
*May 30, 2016*

**Physics**

I haven't even checked the math, but a water level of 3.26 micrometers? That's barely a film, let alone a depth. give me a break! When you get an answer, at least do a sanity check.
*May 30, 2016*

**Math**

well, if their ages now are x and y, then their ages in 7 years will be x+7 and y+7. Now just write your equations and solve them.
*May 30, 2016*

**Math**

I assume you meant e^(x-10) = 10 x-10 = ln10 x = 10+ln10
*May 30, 2016*

**algebra**

well, just substitute 3 for the b and evaluate the result. 12*(2/3)^3
*May 30, 2016*

**maths**

(8+15+x)/3 = 12 now just find x
*May 30, 2016*

**Maths**

each interior angle is the supplement of its exterior counterpart. So, the interior angles are 180-60, 180-130, 180-82 The sum of the interior angles is 360, so ...
*May 30, 2016*