Monday

November 30, 2015
Total # Posts: 35,865

**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*

**Algebra**

huh? You cannot look at the numbers 35 30 25 20 and tell that they are decreasing? You evidently can, since your choice is correct. Also, since the changes in Players are evenly spaced, and so are the changes in Minutes, the function is linear.
*November 9, 2015*

**math models**

y = k/x now just plug in your values: 2 = k/8 k=16
*November 9, 2015*

**math**

x(1+.10*t)=400 x(1+.04*t)=200 Now just solve for t
*November 9, 2015*

**physics**

s = 34.4t - 1/2 at^2 = 61.8 v = 34.4 - at = 0 solving for a, a = 9.57 m/s^2 So, now you know that F=ma
*November 9, 2015*

**Geometry**

R, S, and T are the vertices of one triangle. E, F, and D are the vertices of another triangle. m<R = 60°, m<S = 80°, m<F = 60°, m<D = 40°,? RS = 4, and EF = 4. Are the two angles congruent? If yes, explain how and identify which segment is ...
*November 9, 2015*

**algebra**

PV=kT is constant, so you want V such that .953V = .984*22.5
*November 9, 2015*

**math, a.p. calc**

On the other hand, if you meant g'(x) = (x^2–16)/(x−2) = x+2 - 12/(x-2) then g(x) = x^2/2 + 2x - 12log(x-2) + c g(3) = 9/2 + 6 - 12log(1) + c = 4, so c=-13/2 g'(3) = -7 and the tangent line is y-4 = -7(x-3) and the graph is at http://www.wolframalpha.com/...
*November 9, 2015*

**calculus**

∫[-π,π]∫[-π,π] 1+x^2 siny + y^2 sinx dy dx = ∫[-π,π] 2π dx ...
*November 9, 2015*

**maths**

I have no idea what that means. Try using log_9(x) to mean log (base 9) of x If I try to parse your notation, I'd say 9 log_3(12) = 9 (log_3(3)+log_3(4)) = 9(1+2log_3(2)) = 9 + 18log_3(2) But somehow I doubt that is what you had in mind.
*November 9, 2015*

**Calculus**

cos(a+b) = cosa cosb - sina sinb cos(a-b) = cosa cosb + sina sinb since (x-y)(x+y) = x^2-y^2, that gives us (cosa cosb)^2 - (sina sinb)^2 = cos^2a cos^2b - sin^2a sin^2b = cos^2a (1-sin^2b) - (1-cos^2a) sin^2b = cos^2a - sin^2b = cos^2a - (1-cos^2b) = cos^a + cos^2b - 1 I ...
*November 9, 2015*

**VCU**

2L = 2000 cm^3, so that gives 1g/cm^3 * 2000cm^3 = 2000g
*November 9, 2015*

**VCU**

clearly, that would be 25.0/29.4 g/cm^3
*November 9, 2015*

**trig**

draw a diagram recall the definition of cotθ then you can see that the height h is found using h cot22.9° - h cot38.7° = 27
*November 9, 2015*

**Calculus**

using washers, v = ∫[0,9] π(R^2-r^2) dy where R=2+√(9-y) and r=2 v = ∫[0,9] π((2+√(9-y))^2-4) dy v = 225π/2 or, using shells v = ∫[0,3] 2πrh dx where r = x+2 and h = 9-x^2 v = ∫[0,3] 2π(x+2)(9-x^2) dx = 225π/2
*November 8, 2015*

**Algebra**

make sure that the amounts of glycol in each part add up to the total. If there are x gal of 40%, then the rest (100-x) is 60%, so we have .40x + .60(100-x) = .48(100)
*November 8, 2015*

**Math**

just plug and chug: f(x+h) = 2(x+h)^2+4(x+h) = 2x^2+4xh+2h^2+4x+4h now subtract f(x) = 2x^2+4x and you have 4xh+4h+2h^2 Now divide all that by h, and you have 4x+4+2h lim as h->0 = 4x+4
*November 8, 2015*

**math**

the area of the garden is 96 ft^2 So, you want the walk of width w to also have 96 ft^2 of area. That means that (12+2w)(8+2w) = 96+96 Now just solve for w.
*November 8, 2015*

**Math**

well, just solve 160x/(100-x) = 240 160x = 24000 - 240x 400x = 24000 x = 60
*November 8, 2015*

**Math**

(x-120) * (1 - 2/3) = 1/5 x x = 300 check: 300-120 = 180 2/3 of 180 = 120, leaving 60 50 is 1/5 of 300
*November 8, 2015*

**math**

better study your materials for partitive division story Till you understand that, there's not much hope. I'm sure that there will be examples with the explanation. Or, remember that google is your friend. I used it, and this is my first hit: http://www.math.niu.edu/...
*November 8, 2015*

**Algebra 2**

you are correct. All polynomials are defined over the entire set of real numbers.
*November 8, 2015*

**Math**

number: n 3 less than n: n-3 half of that: (n-3)/2
*November 8, 2015*

**math**

no way to tell. However, the probability that they answered "yes" to the question is 325/(325+294) = 0.525 Assuming the 619 people were chosen at random. Poorly worded problem.
*November 8, 2015*

**Mthombo**

area goes up as the square of the scale. So, the new perimeter: 30 * 1/5 area: 50 * (1/5)^2
*November 8, 2015*

**8th grade pre algebra line segments**

geometric argument for what? You can use a grid and the Pythagorean Theorem to determine lengths of line segments.
*November 8, 2015*

**please give me a site or answer!!!!**

Hard to believe you'd go asking for help without even trying google first. First hit: the one above.
*November 8, 2015*

**technical college**

first, construct your triangle. Then, follow the instructions found here: http://www.mathopenref.com/constincircle.html since the incenter is the intersection of the angle bisectors.
*November 8, 2015*

**math**

recall that C = 2πr
*November 8, 2015*

**Math - Arithmetic question**

yes. since the terms have a constant difference, that just keeps getting added over and over. The sum will always diverge (unless d=0).
*November 8, 2015*

**college**

C works for me.
*November 8, 2015*

**math**

A(.075*15/12) - A(.125*8/12) = 32.50 x = 3120
*November 8, 2015*