Thursday

November 26, 2015
Total # Posts: 35,796

**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*

**math**

You have to watch out for extra factors of 10, which add zeroes to the product. 40 x 50 ≠ 200
*November 10, 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 10, 2015*

**algebra**

10s + 6c = 60
*November 10, 2015*

**Math**

how long does it take to go the 130 ft? 130/25 = 5.2 sec How long to go 15 ft? 0.6 sec So, at 5.2±0.6 the distance will be 15 ft Now what do you think?
*November 10, 2015*

**math**

-4y = 8x y = -2x now what do you think?
*November 10, 2015*

**Geometry**

(180-98)/2
*November 10, 2015*

**Algebra 2**

looks good to me. Though I'd be consistent and either completely factor the result, or expand it. #1 is some of each.
*November 10, 2015*

**Finite Math**

what is P(all red)? Subtract that from 1.
*November 10, 2015*

**math**

We need to know the relative walking/driving speeds. There are lots of solutions otherwise.
*November 10, 2015*

**Math**

looks good
*November 10, 2015*

**math**

80+60 = 140 miles
*November 10, 2015*

**Math**

Hmmm. 6*.60 = 3.60 So, I guess not. That's 12 cents too much. So, knock off 2 cents per can.
*November 10, 2015*

**Pre-Calculus**

using the law of cosines, we know that 7^2+15^2-2*7*15 cosθ = 10^2 cosθ = (7^2+15^2-10^2)/(2*7*15) = 29/35 So, that means the other diagonal, x is x^2 = 7^2+15^2+2*7*15*29/35 = 448 x = 8√7
*November 10, 2015*

**ipc**

PV=kT is constant. That means V/T = k/P is constant. So, you want V such that 30/(273+10) = V/(273+293)
*November 10, 2015*

**maths**

google is your friend. Just search for fractions.
*November 10, 2015*

**need tips**

I suggest that you not help them with their grammar or spelling...
*November 10, 2015*

**geometry**

No diagram.
*November 10, 2015*

**math, physics**

If x is the speed, then since distance = speed*time, 6(x-1.5) = 5(x+1.5)
*November 10, 2015*

**geometery**

recall that the area a = 1/2 r^2 θ Now just convert 68° to radians and plug in your numbers.
*November 10, 2015*

**College Algebra**

x/2 + 150 = 2988
*November 10, 2015*

**Math**

(.32 - 2*.03)/.02
*November 10, 2015*

**Trigonometry**

Since the radii are in the ratio of 5/8, and they both move the same amount of belt, their speed is in the ratio 8/5. So, what is 80 * 8/5 ?
*November 10, 2015*

**trigonometry**

50cos40° assuming 40° is a compass heading. If the angle is measured in the customary way from the x-axis, then you'd have 50sin40°
*November 10, 2015*

**trigonometry**

7cos36°
*November 10, 2015*

**math**

(-54-42)° / (-12°/hr) = -84/-12 = 7 hr
*November 10, 2015*

**pre algebra**

how about 27/31
*November 10, 2015*

**maths**

Not sure what to do with that comma: 4^(x+2)-16, 2^(x+1)+1=0 clearly 2^(x+1)+1=0 has no solutions, since 2^(x+1) is always positive. Maybe you can clarify just what it is you have, and what it is you want...
*November 10, 2015*

**PreCalc/Calc**

review the definition of cotθ. Draw a diagram, and it is clear that the width w is given by w = 10000(cot44°-cot58°)
*November 10, 2015*

**Calc**

since cos(t) starts at the top, and we are starting at the bottom (I assume, though it is not explicitly indicated), h(t) = -cos(kt) the wheel's radius is 7, and the center is 8m up, so h(t) = 8-7cos(kt) The period is 1/3, so 2π/k = 1/3, and k=6π h(t) = 8-7cos(6...
*November 10, 2015*

**Algebra**

w*3w = 108 so, w=6 p = 2(w+3w) = ?
*November 9, 2015*

**math**

xy = 3.6 x+y = 3.8 x + 3.6/x = 3.8 x^2 - 3.8x + 3.6 = 0 (x-2)(x-1.8) = 0
*November 9, 2015*

**math**

start off with the point-slope form. The slope is 5, so y-15 = 5(x-2) Now just rearrange the equation into slope-intercept form.
*November 9, 2015*

**math**

well, just list the digits. You have the place values... 325.312
*November 9, 2015*

**math**

The number of girls in the choir is 4 times the number of boys in the choir. The total number of students in the choir is 60. How many girls are in the choir?
*November 9, 2015*

**Math**

y=9x-5 y=x+11
*November 9, 2015*

**12th**

no idea. How many std away from the mean is considered unusual?
*November 9, 2015*

**precalcus**

P e^(.075*9) = 60000
*November 9, 2015*

**Calculus**

u = x^2 du = 2x dx Now you have 5/2 ∫ u^2 e^u du Now use integration by parts twice.
*November 9, 2015*

**Math**

any odd number cannot be divided into two equal parts.
*November 9, 2015*

**Math**

you have to find the density of vinegar, since weight = density * volume So, look up the density of vinegar in lbs/gal. You will probably find it as g/mL, which you will have to convert into lb/gal. There are unit conversion sites online. One such site, http://www....
*November 9, 2015*

**math**

If you meant that the temperature drops by 5° every 3 hours, you are correct. However, the problem said that the temperature dropped by 5° in each of the 3 hours. In that case, the temperature at 3:00 would be 8 - 3*5 = -7°
*November 9, 2015*

**Algebra 1**

8(x+11) = 123
*November 9, 2015*

**Calculus**

dP/dt = 9√t P(t) = 6t^(3/2)+c P(0) = 700, so c=700 and thus P(t) = 6t^(3/2)+700 as you can see, this function models some slow growth. You sure dP/dt is not proportional to P?
*November 9, 2015*