Sunday

May 1, 2016
Total # Posts: 40,046

**word problems**

naturally, when cost = revenue: 32x = 22x+1830 10x = 1830 x = 183
*April 12, 2016*

**math**

since time = distance/speed, d/12 + d/6 = 12
*April 12, 2016*

**Algebra**

you can get an idea of how these things work here: http://davidmlane.com/hyperstat/z_table.html try using your numbers, and you will see shaded areas.
*April 12, 2016*

**Physics**

nove height?
*April 12, 2016*

**math**

70 + 28n <= 1800
*April 11, 2016*

**math investment problem**

.05*4400 + .09x = 697.00
*April 11, 2016*

**Math**

clearly that would be 72/134
*April 11, 2016*

**Business math - question help**

400*1.1^14 + ... + 400*1.1^1 = 400(1.1^15-1)/(1.1-1) = 12709
*April 11, 2016*

**science**

recall that F = ma now plug in your numbers.
*April 11, 2016*

**Math**

mr and mrs smith, their 2 children and fog want to cross a river in a boat that would hold only 80 kg and both mr. amd Mrs Smith have a mass of 80 kg and both the children have a mass of 40 kg and the dog has a mass of 5 kg explain how they can cross the river in the fewest ...
*April 11, 2016*

**Math**

f' = 1 - 3/x^(2/3) = (x^(2/3)-3)/x^(2/3) f'=0 when x^(2/3) = 3 x^2 = 27 x = ±√27 the tangent is vertical at x=0. f increases where f' > 0: (-∞,√27)U(√27,∞) f decreases where f' < 0: (-√27,√27) The graph ...
*April 11, 2016*

**Geometry**

perimeter grows by a factor of 2, area by 4. So, find the existing values and then scale them up.
*April 11, 2016*

**Math**

well, the width is 7 and the height is 1.
*April 11, 2016*

**Math**

clearly the width is 7, since JK is a horizontal line. so the height is 1.
*April 11, 2016*

**Geometry**

I assume you can find the perimeter and area of the original pyramid. if the sides double, so does the perimeter. But the area, since it is the product of two sides, grows by a factor of 2^2, so it is 4 times as big.
*April 11, 2016*

**Math**

If CD=h and BC=x, then h/x = tan24° h/(x+7600) = tan16° or, h = 0.4452x h = 0.2867x + 2179.2649 0.4452x = 0.2867x + 2179.2649 BC = x = 13750 CD = h = 6121
*April 11, 2016*

**Math**

two distinct solutions means that the discriminant is positive. So, we need k^2 - 64 > 0 also, we need (k±√(k^2-64))/4 to be an integer. So, k±√(k^2-64) must be a multiple of 4. and k^2-64 must be an integer. so, what pythagorean triples do you ...
*April 11, 2016*

**Math**

the ball hits the ground when y=0. If you want a fraction, then let's get rid of the decimals: y = 1/10 (-49t^2 + 35t + 50) = 1/10 (7t+5)(10-7t) y=0 when t = 10/7
*April 11, 2016*

**Pre algebra**

6n-8 = 13 + 4(n+3) 6n-8 = 13+4n+12 2n = 33 n = 33/2
*April 11, 2016*

**maths help!??**

since time = distance/speed, 4/9 + x/2 = 1 That will tell you the rest of the distance. I suspect you have garbled your question, since they told you his speed for the first 4km was 9km/hr.
*April 11, 2016*

**Math**

translate up 3 means add 3 to all the y-values. left 3 and up 2 means subtract3 from x and add 2 to y. just think of the axes, and which directions are positive and negative. (4+2 , 3-5)
*April 11, 2016*

**Algebra 2**

tan^4 - sec^4 = (tan^2-sec^2)(tan^2+sec^2) = (tan^2-(1+tan^2))(tan^2+(1+tan^2)) = (-1)(1+2tan^2) = -2tan^2-1 Reiny, imagine the missing x's are present!
*April 11, 2016*

**Math**

the first digit must be 3,5,7 the other digits can be 1,3,5,7,9 since the 1st digit cannot be repeated, that means the last 3 digits must be formed using only 4 of the available choices, giving 4*3*2 choices. So, since the 1st digit can be chosen 3 ways, there are 3*4*3*2 ways...
*April 11, 2016*

**Math**

using the sum of tangents formula, tan(arctan x + arctan y) = tan(arctanx)+tan(arctany) ----------------------------- = tan(pi/4) 1 - tan(arctanx)-tan(arctany) (x+y)/(1-xy) = 1 x+y = 1-xy x+xy+y = 1
*April 11, 2016*

**Factor out the Greatest Common Factor (GCF)**

well, take a look 45d^3 = 9d^2 * 5d 18d^2 = 9d^2 * 2 so, what do you think?
*April 11, 2016*

**maths**

length = w+2
*April 11, 2016*

**Calculus**

check the related questions below. for extrema as described above, you need f' = 3ax^2+2cx = 0 at x=0 and -4, so x(3ax+2c) = 0 -12a+2c = 0 You also have two points, so -64a+16c+d = 9 0a+0c+d = 6 a = 3/32 c = 9/16 d = 6 so, that means that f(x) = 3/32 x^3 + 9/16 x^2 + 6 the...
*April 11, 2016*

**Math**

Remember your Algebra I. The max height is represented by the vertex of the parabola. As with all quadratics, the vertex is at t = -b/2a. So, for #1: t = -122/-32 = 3.8125 seconds use the same logic on #2.
*April 11, 2016*

**Vectors, Math**

Since |B| = 4, B = <4/√2,-4/√2> = <2√2,-2√2> AB = B-A = (2√2-3,-2√2-2)
*April 11, 2016*

**math**

b/a = tan 60° = √3 The ratio of the volumes is thus πb^2a/πa^2b = b/a = √3
*April 11, 2016*

**calculus 2**

What, you don't have any work to show? You can verify your results using the handy calculator at http://keisan.casio.com/exec/system/1392171850
*April 11, 2016*

**fds**

all of them
*April 11, 2016*

**math**

you might show your work, so we could check your method. each dogs eats 3.5/7 = 0.5 kg/day 16 dogs eat 8 kg/day That's 720 kg for 90 days Or, 1584 lbs. That's 63.36 bags I guess it depends on how many days you use for 3 months. 91 days gives 64.06 bags
*April 10, 2016*

**Math geometry**

w/146 = cot 50°
*April 10, 2016*

**Geometry**

you are correct if the "thickness" means the height of the material on the ground.
*April 10, 2016*

**Calculus derivatives**

well does that not mean that dy/dx = -1? Using implicit differentiation, 2x + y + xy' + 2yy' = 0 y' = -(2x+y)/(x+2y) so, you want (2x+y)/(x+2y) = 1 2x+y = x+2y y = x plug that into the original equation and you get x^2 + x^2 + x^2 = 1 x^2 = 1/3 so, at (1/√3,1...
*April 10, 2016*

**Math**

If there are x wheat and y oats, x <= 200 y <= 300 x+y <= 250
*April 10, 2016*

**Math :)**

I'd say high volume, since that minimizes the surface area, making the cube last longer. High surface area (lower volume) means faster cooling, but the cube does not last as long.
*April 10, 2016*

**Calculus**

nope 4x/(x-5) -> 20/0 this is just algebra. Recall your rational functions work? Vertical asymptote at x=5.
*April 10, 2016*

**Math**

If Owen has x and Charley has y, then we are told that x-50 = y+50 (x+100) = 4(y-100) Now just find x.
*April 10, 2016*

**Calculus**

This is just ∫∫∫ dz dy dx using the appropriate limits Unfortunately, the plane 2x+z=3 is a vertical plane, and does not bound a region of the paraboloid.
*April 10, 2016*

**math**

8914*1.0136^t = 15000 t = 38.53 Better check your math.
*April 10, 2016*

**Math**

these are headings, not bearings. I do not get a right triangle. I get an angle of 27+90+27= 144 at the turning point. To get the final location, convert each side to its x- and y-components. Add them up, and you can then get the angle θ using tanθ = y/x and then the...
*April 10, 2016*

**Math: Parametric Equations**

since sin^2(t)+cos^2(t) = 1, (2+4cos(s))^2 + (3+4sin(s))^2 = 1 See where that gets you.
*April 10, 2016*

**maths**

set up a diagram. You can see that if the angle to the top of the building is a, then x/9 = cot(a) x/16 = cot(a+θ) θ = arctan(x/9) - arctan(x/16) dθ/dx = 0 when x=12 as shown here: https://www.wolframalpha.com/input/?i=arctan%28x%2F9%29+-+arctan%28x%2F16%29
*April 10, 2016*

**maths**

tan(A/2)
*April 10, 2016*

**math**

Assuming the usual carelessness with parentheses, I get 4^(x+3) = 32(2^(x+y)) 2^(2(x+3)) = 2^5*2^(x+y) 2x+6 = 5+x+y x = y-1 9^(y-1) + 3^y = 10 3^(2y-2) + 3^y = 10 3^(2y)/9 + 3^y = 10 3^(2y) + 9*3^y - 90 = 0 (3^y + 15)(3^y - 6) = 0 3^y = 6 y = log6/log3 x = y-1 That answer is ...
*April 10, 2016*

**maths**

logy/log2 = log_2(y) logy/log4 = log_4(y) since 2^2 = 4, log_2(y) = 2log_4(y) = log_4(y^2) so, now we have log_4(y^2*y) = 6 log_4(y^3) = 6 y^3 = 4^6 y = 4^2 = 16
*April 10, 2016*

**math**

2lg5 = lg(5^2) lg[(x+14)/(x-2)] = lg25 (x+14)/(x-2) = 25 x+14 = 25x-50 24x = 64 x = 8/3
*April 10, 2016*

**geometry (check answers)**

a no b many c many d one e no f no
*April 10, 2016*

**Calc**

a little check will show that h = A/w - w/4 So, the perimeter is (assuming the triangle is isosceles) p = w+2h+w√2 = w(1+√2) + 2(A/w - w/4) = (1/2 + √2)w + 2A/w dp/dw = (1/2 + √2) - 2A/w^2 dp/dw = 0 when w = 2√(A/(2+√2)) h = (1+√2)/2...
*April 9, 2016*

**LOGARITHM**

Assuming you meant the log of (2x-1)^2, then that means (2x-1)^2 = e^7 2x-1 = e^3.5 = 33.115 2x = 34.115 x = 17.0577 Looks ok to me. of course, there is the other root using 2x-1 = -33.115
*April 9, 2016*

**Math: Parametric Equations**

cos(4t) has period pi/2 sin(6t) has period pi/3 so, you get the entire curve using the interval [0,pi] as indicated by the note next to the graph at the suggested URL.
*April 9, 2016*

**Math**

of course he is right. The actual room is 18 times as big as the drawing. So, any length on the drawing, times 18, is the length in the room. Any length in the room, divided by 18, is the length in the drawing. That's the whole purpose of scale drawings - to represent the ...
*April 9, 2016*

**History**

indeed
*April 9, 2016*

**History**

What powers did Parliament have in the Bill of Rights?
*April 9, 2016*

**Math: Trigonometry**

we want sin(x+n) = cos(x) sin(x)cos(n) + cos(x)sin(n) = cos(x) we need cos(n)=0 and sin(n)=1 This is true only for n = 2k*pi + pi/2 for k=0,1,2,3... that is pi/2, 5pi/2, 9pi/2, ... 100 * 2/pi = 63.6, so the last entry in the list is 61pi/2 = 95.8
*April 8, 2016*

**History**

thanks
*April 8, 2016*

**History**

yes i would like help with the assignment, like good sites onto where i could find information of this or something
*April 8, 2016*

**History **

1. What powers did Parliament have in the Bill of Rights? 2. Why was King James removed from the throne? 3. Do you think the people of England were more in favor of King William and Queen Mary in being the King and Queen than King James II? Why or nor why not? Support your ...
*April 8, 2016*

**Algerba**

sure thing. When you encounter complicated math problems, just take a deep breath and realize that since you only know a few simple rules for working with the stuff, the big mess can always be broken down into simple pieces that you can do easily, using the rules you know.
*April 8, 2016*

**Algerba**

sure. Note that 4-4=0, so that term goes away. Also, 4/2 = 2. Then you have 3r- 4/2 +4r-12+13s+5r+5(9-r)-6r+2(-4)-5(2s)+2(9+3r)+2-3s = 57 remove the parentheses: 3r-2+4r-12+13s+5r+45-5r-6r-8-10s+18+6r+2-3s = 57 Now collect all the r and s stuff, and collect all the constants: ...
*April 8, 2016*

**Algerba**

ah. never mind. After you clear away all the noise, you are left with 7r+43 = 57 7r = 14 r = 2 the value of s does not matter; it can be anything.
*April 8, 2016*

**Algerba**

still, you want r or s?
*April 8, 2016*

**Algerba**

you have two variables, and unmatched parentheses. You want to solve for r or s?
*April 8, 2016*

**Calculus**

works for me. I did the integral directly, using ∫[0,1] 2π(1-y) arccos(y) dy and got the same answer. I like your technique of avoiding the arccos, though.
*April 8, 2016*

**Math**

better look up the inflation rates between then and now.
*April 8, 2016*

**Math 10- Relations & Functions**

y = 4x-8 C(n) = 14n+5 8x+12 = 132 F(6) = 8*6 + 12
*April 8, 2016*

**Math Help!!!**

looks good to me.
*April 8, 2016*

**geometry**

I'd start with this: The circle's equation is (x - a/2)^2 + (y - b/2)^2 = (a^2+b^2)/4 If a chord intersects the x-axis at x=c, then the slope of the chord is (b)/(a-c) so, the equation of the chord is y = b/(a-c) (x-c) and the length of the chord is 2sqrt((a-c)^2 + b^2...
*April 8, 2016*

**Algebra**

√363 - 3√27 = √(121*3) - 3√(9*3) = 11√3 - 3*3√3 = 2√3
*April 8, 2016*

**Algebra 1**

n = n^1 so, adding exponents, n^-4•n = n^-4 • n^1 = n^(-4+1) = n^-3 or, since n^-4 = 1/n^4, 1/n^4 • n = n/n^4 = 1/n^3
*April 8, 2016*

**mathematics**

all sides are 10, so its base is 10. 10h = 84 h = 84/10 = 42/5
*April 8, 2016*

**Math**

well, what is 100% of 25? Naturally, that's 25, since 100% is all of something. 500% is 5 times 100%, so that is just 5*25 = 125 a little thought can help a lot while you're waiting, rather than whining about it.
*April 7, 2016*

**Mathematics**

yes. the angle is 1/5 of 360°, or 72° and that's rotational symmetry, not system.
*April 7, 2016*

**math**

4.1x10^5 = 4.1 x 100,000 = 410,000
*April 7, 2016*

**Math**

10*9*8 = 720
*April 7, 2016*

**Algebra**

-7 < y <= 3
*April 7, 2016*

**Math**

1/5 + 1/4 = 9/20 so, the rest is 11/20 11/20 x = 11 so, 1/20 x = 1 x = 20 1/5 of 20 is 4 to her brother
*April 7, 2016*

**calc 2**

for our function, y' = 6k(kx)^5 so, we want other curves whose slope is y' = -1/(6k^6) x^-5 y = 1/(24k^6 x^4) or, to make things look more similar, y = 1/(24k^2) (kx)^-4
*April 7, 2016*

**Newtons Second Law**

Net force is 7500-2200-5000 = 300N F = ma, so a = 300N/1200kg = 0.25 m/s^2 the actual speed of the car does not matter.
*April 7, 2016*

**Algebra**

The fill rate is clearly 825 ft^3/hr At 10 hours, that will be 8250 ft^3. no idea of the percent filled. How big is the silo?
*April 7, 2016*

**pre ap math**

cool!
*April 7, 2016*

**Math**

factor out the 9: 9(y^2-9) difference of squares: 9(y-3)(y+3)
*April 7, 2016*

**Algebra**

If there were x oz of almonds, then the rest (300-x) was tea. 0.95x + 2.15(300-x) = 1.85(300)
*April 7, 2016*

**Math**

3 yds = 108 in. So, length+width = 54 in. Starting with w=6, we thus have dimensions of 6,48 7,47 ... 12,42
*April 7, 2016*

**Algebra**

looks good to me.
*April 7, 2016*

**Algebra**

1/5 + 1/12 = 1/x
*April 7, 2016*

**chemistry**

66s is 6 half-lives, so 49.0 * (1/2)^6 = 0.765 μg
*April 7, 2016*

**Chemistry**

80(1/2)^t = 10 (1/2)^t = 1/8 t = 3 so, 45 days is 3 half-lives
*April 7, 2016*

**Algebra**

since time = distance/speed, 132/(x+11) = 132/x - 2 x = 22 6 hrs at 22 mph 4 hrs at 33 mph
*April 7, 2016*

**Algebra**

If it takes A x days, it takes B 2x days. 1/x + 1/(2x) = 1/5 3/(2x) = 1/5 x = 15/2 So, it takes B 15/2 days, and A 15/4 days
*April 7, 2016*

**Algebra II**

so, 8=4p p=2 that is the distance from the vertex to the focus. All you need to do is (a) read what we gave you (b) think about it a bit
*April 7, 2016*

**Algebra II**

for the parabola y^2 = 4px the vertex is at a distance p from the focus.
*April 7, 2016*

**Math**

which are the right angles?
*April 7, 2016*

**chemistry**

142km * 1gal/27mi * .6214mi/km * 3,78L/gal = 12.35L
*April 7, 2016*

**Algebra**

If x at 2 pts, then 24-x at 3 pts. So, adding up all the points, 2x + 3(24-x) = 53 x = 19 for 2-pts so, 24-x = 5 for 3-pts
*April 7, 2016*

**math**

In QI, x>0 and y>0 so, where are x<0 and y<0 ?
*April 7, 2016*

**Chemistry**

What is the mole fraction of NaBr in an aqueous solution that contains 20.1% NaBr (weight/weight%)?
*April 7, 2016*