Sunday

November 29, 2015
Total # Posts: 35,840

**Rationa Numbers**

8^-2 = 1/8^2 = 1/64
*November 13, 2015*

**Math**

glide: (-3,3) -> (2,3) reflect: (2,3) -> (2,-1) I suspect a typo.
*November 13, 2015*

**Math - Logarithms**

by definition, ln(x) is the power of e you need to get x. Just as log_10(100)=2 because 100=10^2 b^(log_b(N)) = log_b(b^N) = N ln(e^e) = e*ln(e) = e*1 = 1
*November 13, 2015*

**Math - Logarithms**

You could use some parentheses. I'd have done it like this, combining the ln(2x) terms first: 4ln(2x) + ln(6/x) - 2ln(2x) 2ln(2x) + ln(6/x) 2ln2 + 2lnx + ln6 - lnx ln4 + ln6 + lnx ln(24x) Or, doing it kind of your way, 4ln2x + ln(6/x) - 2ln2x ln(16x^4) + ln(6/x) - ln(4x^2...
*November 13, 2015*

**calculus**

so, whatcha got to show us?
*November 13, 2015*

**Calculus**

you can confirm your work here: http://mathworld.wolfram.com/RiemannSum.html
*November 13, 2015*

**Trigonometry**

review the definition of tan(x). Draw a diagram. You will see that the height is 407 tan67° - 407 tan36°
*November 13, 2015*

**Algebra 2**

substitution: x = 13-4y, so 2x+3y = 2(13-4y)+3y = 6 26-8y+3y = 6 -5y = -20 y = 4 so, x=13-4y=13-4*4 = -3 Elimination: Multiply the 1st equation by 2, and you get 2x+8y=26 2x+3y=6 Now subtract and you have 5y=20 and so on as above,
*November 13, 2015*

**algebra 1**

|x|-5 = 7 |x| = 12 So, I'd say (A) You know, your keyboard has || characters...Look right above the \ character which you typed.
*November 13, 2015*

**Al;gebra 1**

assuming a nonzero interior rectangle, 2p < 20
*November 13, 2015*

**math**

if x is positive, so is 1/x. If x is negative, so is 1/x So, the graphs lie in QI and QIII apply that logic to m(x) and n(x)
*November 13, 2015*

**Calculus 1**

or use one of the various online Newton method calculators to verify your work.
*November 13, 2015*

**Calculus 1**

f(x) = x^3+1 - 7/x f'(x) = 3x^2 + 7/x^2 Now let 'er rip
*November 13, 2015*

**Calculus 1**

see related questions below.
*November 13, 2015*

**Physics**

well, just plug in your numbers: F = Gm1m2/r^2
*November 13, 2015*

**@Writeacher**

Dang! I missed a perfect opportunity to post that Latin version.
*November 13, 2015*

**And for my next trick...**

!?
*November 13, 2015*

**Math**

If x were correct, then (40-x) were wrong. Assuming you answered all 40 questions, x/2 - 3(40-x) = 0
*November 13, 2015*

**maths**

-3+(-8) = -3-8 = -11
*November 13, 2015*

**Math**

when the wheel has turned through an angle θ, P is at (x,y)=(cosθ,sinθ). So, since the x-coordinate is at cosθ, Q has moved 1-cosθ left from its starting point. You don't say how fast the wheel is turning, so there's no way for me to know how ...
*November 13, 2015*

**Calculus**

visit http://keisan.casio.com/exec/system/1244946907 and you can use the function f(x) = x^2-27 f'(x) = 2x to approximate √27
*November 13, 2015*

**math**

the inside radius is r=(3 - 5/12) ft So, its volume is πr^2 h Just plug in your numbers. That will give you the volume in ft^3. Then just apply the conversion factor for gal/ft^3.
*November 13, 2015*

**Math**

I has a period of 1/60 seconds. Since it starts at zero, it is a maximum 1/4 period into each cycle, or t=1/240. Then again every 1/60 of a second. It is a minimum at half a period, or 1/120 seconds after each maximum. Just review the properties of the sine function.
*November 13, 2015*

**Math**

play around here to learn how the Z table stuff works: http://davidmlane.com/hyperstat/z_table.html
*November 13, 2015*

**Math**

because 21/28 = 3/4
*November 13, 2015*

**math**

Can't tell without knowing how wide the tiles are, since the border will have 4 corners. If the tiles have width w, then if the pool's width is x, 2(x+20x)+4w = 150
*November 12, 2015*

**World History**

thank you
*November 12, 2015*

**World History**

When do the number of social movements increase? a- During an economic expansion b- during population shrinkage c- during political stability d- when a society experiences a cultural crisis My answer is D
*November 12, 2015*

**Precalc**

15000+9*600 = 20400 At the start of the 10th year, she has had only 9 increases. 10/2 (15000+20400) = 177000 8/2 (2*1500 + 7*300) = 20400 Looks like a small review of A.P.'s is in order.
*November 12, 2015*

**tech math**

The surface area of each cylinder is πdh = π*2.5*4.9 = 38.48 in^2
*November 12, 2015*

**math**

yes, but you are dealing with a square, where a=b. Plug that in and see what you get.
*November 12, 2015*

**Pre-Calculus**

10000 * 0.9^6 On the nth bounce it has to go a round trip, of height 30*(2/3)^n, So we want the 1st 4 terms of a G.P. with a = 30 r = 2/3 30 + 2*S4 = 30+2*30(1 - (2/3)^4)/(1-2/3) = 174.44 ft
*November 12, 2015*

**Math**

If the printed area has width x and height y, xy=382 The area of the poster is a = (x+18)(y+16) = (x+18)(382/x + 16) = 16x + 670 + 6876/x For minimum area, da/dx=0, so 16 - 6876/x^2 = 0 x = 3/2 √191 Now you can figure the poster dimensions.
*November 12, 2015*

**Integral Calculus - Series**

since 1/n^k converges for k>1, and (4n+7)/(3n^3-8n) < (5n)/(3n^3) < 2/n^2 it converges. Note that for sufficiently large n, 4n+7 < 5n. And since 3n^3-8n < 3n^3, a smaller denominator makes for a larger quotient.
*November 12, 2015*

**Algebra HELP!**

graph the two lines. Then see where they intersect. That is the only way to solve using graphs. each line has a slope. What do you mean by "my slope"?
*November 12, 2015*

**Math**

no calculator? 5*10 * 5*10 5*5 * 10*10 25 * 100 2500
*November 12, 2015*

**Science**

wire: a good conductor coating: a good insulator A little study should turn up some examples of each. Or, look at the lamps in your house...
*November 12, 2015*

**Energy science**

a pump is lowered into the hole, and the oil is pushed up. Or, a pipe inside another pipe is pushed down, and air or water is pumped down the outside, and oil is thus pushed up the inside. Or, google pumping oil from deep wells.
*November 12, 2015*

**science**

kitten boots, obviously.
*November 12, 2015*

**Science**

Power = Amps * Volts
*November 12, 2015*

**algebra**

a+d = -6 a+4d = 48 so, 3d=54 d=18 so, a=-24 and the sequence is -24 -6 12 30 48 ...
*November 12, 2015*

**Maths**

It's already factored! You need to review how to multiply polynomials It all hinges on the distributive property. (x+1)(x-3) = x(x-3)+1(x-3) = x^2-3x + x-3 = x^2-2x-3 Now multiply that by (x-4) and you have (x^2-2x-3)(x-4) = x^2(x-4)-2x(x-4)-3(x-4) = x^3-4x^2-2x^2+8x-3x+12...
*November 12, 2015*

**Algebra Probability PLEASE HELP**

oops. my bad. That would be 1/4 and 3/4, not 1/5 and 4/5
*November 12, 2015*

**Algebra Probability PLEASE HELP**

As you know, the probability of answering k out of n questions correctly, given P(correct) = p, is nCk * p^k * (1-p)^(n-k) So, since you have n=5 k=3 p=1/5 p(3 of 5) is 5C3 * (1/5)^3 * (4/5)^2 = 32/625 That is the theoretical probability. For experimental, you'd need to ...
*November 12, 2015*

**Probability**

No idea. Take the test a few times and see how many of those times you get 3/5 correct.
*November 12, 2015*

**ALGEBRA**

well, if 9 is one factor of 36, the other is 4. So, since you have +5x, you need (x+9)(x-4)
*November 12, 2015*

**Calculus 1**

A quick look at the graph shows that the point we want will be somewhere in the interval [pi,2pi]. The line through (0,0) and (x,-4sinx) is y = -4sinx/x we also know that at any point x, the slope is y' = -4cos(x) So, we need -4sin(x)/x = -4cos(x) tanx = x So, let f(x) = ...
*November 12, 2015*

**math**

600 = 505+95 = µ + 0.856σ So, you want to look up in your Z table for P(Z<.856)
*November 12, 2015*

**Calculus**

it's unbounded. If I assume you mean the area between the x-axis and the curve, to the left of x=7, then we have ∫[-∞,7] 7/√(7-x) dx which is unbounded. If you mean the piece to the right of the y-axis, then ∫[0,7] 7/√(7-x) dx = 14√7 try...
*November 12, 2015*

**Geometry**

correct. Naturally, the length and width of a square are the same!
*November 12, 2015*

**Geometry**

well, area = length * width...
*November 12, 2015*

**Calculus**

(a) ∫[0,4] 300000+750000t dt = 7,200,000 Now you can use that to find the present value
*November 12, 2015*

**chemistry**

(4π/3 * 0.05^3 cm^3) * 13.6g/cm^3 * 1mol/200g * 6.023*10^23atom/mol = 2.144x10^19 atoms
*November 12, 2015*

**math**

every number not equal to -4 is greater than or less than -4...
*November 12, 2015*

**maths**

j-5 = 54 Can you take it from there?
*November 12, 2015*

**Math**

(1/3)(5*336)
*November 12, 2015*

**math**

If n<1, n < 1/n If n=1, n = 1/n If n>1, n > 1/n
*November 12, 2015*

**math**

m < 0 subtract m from both sides, and you have 0 < -m
*November 12, 2015*

**math**

how about some spaces or parentheses to show factors?
*November 12, 2015*

**math**

Let the numbers be x and y, with x < y 2y = 2x+18 x/3 + y/5 = 21 Now just solve as usual.
*November 12, 2015*

**algebra**

in more conventional notation, y = 2x^2 + 3x + 2 As with all graphs, pick a few points, plot them, and connect them with a smooth curve. You know this one is a parabola, so you don't have to go in blind. y = 2(x^2 + 3/2 x) + 2 = 2(x^2 + 3/2 x + 9/16) + 2 - 2(9/16) = 2(x + ...
*November 12, 2015*

**Algebra**

h^2 + 15^2 = 42^2 t=k/R So, Rt is constant. You want t such that 500t = 650*50 since time = distance/speed, 45/(12-x) + 45/(12+x) = 8
*November 12, 2015*

**Calculus 1**

let f(x) = (x-9)^2 - ln x f(7) = 4-ln7 > 0 f(8) = 1-ln8 < 0 f(9) = 0-ln9 < 0 f(10) = 1-ln10 < 0 f(11) = 4-ln11 > 0 So, you can see where to make your guesses.
*November 12, 2015*

**Calculus 1**

Visit http://keisan.casio.com/exec/system/1244946907 and type in your functions. You will see that the root is -0.68233 You can also see this at wolframalpha.com When you try to solve a problem and don't get a satisfactory answer, it would help if you showed your work. ...
*November 12, 2015*

**8th grade math**

note that y grows by 85 when x grows by 1. So, first guess: y = 85x But 85*1 = 85, and y(1) = 135. So, now how can you accommodate that fact?
*November 12, 2015*

**8th grade math**

note that as x increases by 1, y increases by 3. So, the first guess would be y = 3x But when x=1, 3x=3, but y=7. So, y = 3x+4
*November 12, 2015*

**algebra**

type in your equations here and see all the steps: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*November 12, 2015*

**8th grade math**

clearly y=3x+42 does not work for output=42. However, if this is a continuation if in-1 out-45 in-2 out-90 Then the relation is clearly y = 45x
*November 12, 2015*

**8th grade math**

many possibilities. One is out = 3*in + 42
*November 12, 2015*

**math**

sorry. The branches split at x = -3, not x=0.
*November 11, 2015*

**math**

since f is not single-valued, it has no inverse. For x>=0, f^-1(x) = √((x+3)/2) There is also a branch for x <= 0
*November 11, 2015*

**Algebra 1 grade 9**

well, 51 = 4*12 + 3
*November 11, 2015*

**science**

what is a 360cm box? a cube 360 cm on a side? If so, then (360 cm)^3
*November 11, 2015*

**math**

(4.2z)(-5y-3) (4.2z)(-5y)+(4.2z)(-3) -21.0yz - 12.6z
*November 11, 2015*

**Math**

How do you get DB and EC? There are separate triangles. Apparently they have one point (A) in common.
*November 11, 2015*

**Geometry**

find the side lengths. By the law of since, the angle measures are in the same order as the side lengths.
*November 11, 2015*

**Algebra**

break-even where R=C, so just solve 20,000 + 25x + 0.2x^2 = 475x − 0.8x^2 Rearrange and collect terms, and then just use the quadratic formula.
*November 11, 2015*

**Math**

all of the questions you keep asking have been answered above. I think you need to review what it means to be prime.
*November 11, 2015*

**Math**

so, to get the correct factorization, factor all the non-primes: 22 * 3 * 54 * 8 * 112 = 2*11*3*2*3^3*2^3*2^4*7 = 2^9 * 3^4 * 7 * 11
*November 11, 2015*

**Brain excel**

As always, draw a diagram. You can then see that PQ/18 = tan35° RS^2 = 18^2+24^2 I don't know which is the typo, but you have angle of Q from S twice. Anyway, use the tan function to get the other angle, as I did above, but this time you know PQ, and have to get the ...
*November 11, 2015*

**math!!!**

is there a question in there somewhere? 1t step is probably to add -1.002+0.93 I assume you can handle that much, right?
*November 11, 2015*

**algebra**

clearly it is 66/101 Just convert that to a decimal percent.
*November 11, 2015*

**precalcus**

You cannot have a vertical asymptote at x=3 and a removable discontinuity at x=3.
*November 11, 2015*

**MATH HELP**

#3 Nope. √9 is a radical, but is rational #4 ok #5 a perfect cube has three equal factor 125 = 5*5*5 #6 ok, if -9 was a typo for 9 #7 ok #8 Nope. 5^2 = 25 6^2 = 36 which is closer to 35? #10 Nope. The squares are 16,25,36,49 #11 ok #12 ok
*November 11, 2015*

**Precalculus**

#1: S = 3000(1-1/2^17)/(1 - 1/2) #2: S = 10/2 (2*7+2) #3: S = 1(√2^12 - 1)/(√2-1)
*November 11, 2015*

**College Physics**

A 10 kg mass (initially at rest) is attached to a rope, which is wrapped about a thin-walled hollow cyclinder of diameter D = 50 cm and mass = 20 kg. After the 10 kg mass drops a distance of 1.4 m, what is the angular speed of the cylinder? What is the acceleration of the ...
*November 11, 2015*

**Algebra**

109/3 = 36.3 103/3 = 34.3 So, assuming no partial tiles are used, the job needs 37*34=1258 Hmm. Not a choice. So, assuming the cut pieces can be used, (109*103)/(3*3) = 1247.4, so A seems reasonable.
*November 11, 2015*

**Algebra**

nope. 10 decreased by 3 is 10-3 You want 60 - n/4
*November 11, 2015*

**math**

deci- means 1/10 So, a liter contains 10 deciliters You just need to study your prefixes.
*November 11, 2015*

**math**

A = kB^2/C So, AC/B^2 = k and is constant. So, you want A such that 72A/144 = 6*100/25
*November 11, 2015*

**Algebra**

you are right.
*November 11, 2015*

**Algebra**

Why the 4w? I see no mention of "4 times the number of white marbles" How about 8+4+x = 24
*November 11, 2015*

**algebra**

9/16 * 10/7 = 90/112 = ...
*November 11, 2015*

**math**

If divisible by 5, the number must end in 0 or 5. Now what do you think?
*November 11, 2015*

**Math**

If the parts are x and y, we have 3x=2y x+y=120 or, 3x+3y = 360 2y+3y = 360 y = 72 x = 48
*November 11, 2015*

**physics**

clearly, it is (30km/hr)/(1/2 hr) = 60 km/hr^2
*November 11, 2015*

**Unit 1**

36-6x
*November 11, 2015*

**Calculus 1**

If the triangle has side x, and the square has side y, then 3x+4y = 23 The area is a = √3/4x^2 + y^2 = √3/4 x^2 + (23-3x)^2/16 = 1/16 (9+4√3)x^2 - 138x + 529) so, for max/min area, we need da/dx=0, or (18+8√3)x - 138 = 0 x = 69/(9+4√3) = 4.332 So...
*November 11, 2015*

**Calculus**

Integration by parts is just the product rule in reverse: d(uv) = u dv + v du ∫u dv = uv - ∫ v du Let u = x^2 du = 2x dx dv = cos(3x) dx v = 1/3 sin(3x) ∫x^2 cos(3x) dx = (x^2)(1/3 sin(3x)) - (2/3)∫x sin(3x) dx Let u = x du = dx dv = sin(3x) dx v = -1/3...
*November 11, 2015*

**Math**

multiply the ratios by 16, and you get 48:16:48 Now add those up. It is not 1 apple to 3 cherry. It is 1 cherry to 3 apple.
*November 10, 2015*