Thursday

February 11, 2016
Total # Posts: 37,579

**math**

man is half as high, so shadow is half as long.
*January 30, 2016*

**math**

P/20 = 3/4, so P=15 (15+5)/(20+5) = 20/25 = 4/5
*January 30, 2016*

**COMPUTERS**

PARAMETER (PI = 3.141592653589793) A = 2*PI*2**2 some dialects of FORTRAN define constants differently.
*January 30, 2016*

**trigonometry**

this particular sec/tan example falls out nicely: 1/(secx - tanx) = secx + tanx 1 = (secx+tanx)(secx-tanx) 1 = sec^2(x) - tan^2(x) one of the fundamental identities, arising immediately from sin^2 + cos^2 = 1 by dividing by cos^2
*January 30, 2016*

**Physics**

well, 50keV = 8.01 x 10^-8 ergs
*January 30, 2016*

**math**

well, a layer of water 1cm deep will have volume 49π cm^3. The volume of the cubes is 154 cm^3 That should tell you how to figure the depth of water occupied by the cubes.
*January 30, 2016*

**math**

c+(c+13)=27
*January 30, 2016*

**Math**

c'mon, guy - use what you know abot APs: (a+2d)+(a+6d) = 12 (a+2d)(a+6d) = 32 Now just solve for a and d, then you want a+8d. Hint: 4*8 = 32
*January 30, 2016*

**Quick calc question**

That would be f'(g(2x))g'(2x)(2x)' = f'(g(2))g'(2)(2) = f'(4)g'(2)(2) = 2*4*2 = 16
*January 30, 2016*

**Quick calc question**

why all the wordy mumbo jumbo? Ever heard of math symbols? f(x) = (1-x)/(1+x) g(x) = x/(1+x) f(g) = (1-g)/(1+g) = (1-(x/(1+x)))/(1+(x/(1+x))) = 1/(2x+1) the domain excludes x = -1, since g is not defined there. It also exludes x = -1/2, as shown by the final form of the fraction.
*January 30, 2016*

**analytic geometry**

distance extremes are at the ends of the semi-axes. You know that a=93, and c/a = 1/60. And, b^c+c^2=a^2. Hard to figure just what you are after with the ships, but apparently you want the angle ACB. Angle CAB is arctan(120/80)+10° To find the distance CB, use the law of ...
*January 30, 2016*

**analytic geometry**

The circle is (x-2)^2 + (y-1)^2 = 25 The shortest distance is along the line from the center (2,1) to (10,7). So, find the distance between those two points, and subtract 5, the radius of the circle. For the longest distance add 5, to the opposite end of the diameter. The ...
*January 29, 2016*

**Math**

-1/2 0 -3.14
*January 29, 2016*

**Math**

3000/(12.5*60) = 4 cents/min now you can answer the questions.
*January 29, 2016*

**Geometry**

the rectangle could be long and skinny: 1 x 2300 or approximately square: 46 x 50 Or, if you do not insist on integer dimensions, pick any width (w) you like, and the length is 2300/w.
*January 29, 2016*

**Math (help please)**

if the polygon has six sides, it is a hexagon.
*January 29, 2016*

**MATHS**

2(10+x) = 37+x
*January 29, 2016*

**math**

looks ok to me.
*January 29, 2016*

**Math**

well, that's obviously 12i^2 = -12
*January 29, 2016*

**Music**

seems to me that "drums" is the only member of the rhythm section. the others are strings or winds.
*January 29, 2016*

**Geometry**

multiply by 15 to get rid of those pesky fractions: x/3 = x + 2/5 5x = 15x + 6 10x = -6 x = -3/5 or, x/3 = (x+2)/5 5x = 3(x+2) 5x = 3x+6 2x = 6 x = 3
*January 29, 2016*

**Calculus**

as written, -y - xy' = 3y^2 y' (3y^2+x)y' = -y y' = -y/(3y^2+x)
*January 29, 2016*

**physics**

well, the resultant C = A+B = 5i-j+k |C| = √27 so, the unit vector is C/√27
*January 29, 2016*

**math**

90-x = (180-x)/5 - 10 now just solve for x.
*January 29, 2016*

**Math**

30 = 3*10 The 3-letter pattern repeats 10 times. so, Z
*January 29, 2016*

**maths**

sphere: v = 4/3 pi r^3 = 500pi/3 = 524 cm^3 The diameter of the sphere is equal to the depth of the water, so it will be completely submerged as the water level rises.
*January 29, 2016*

**Trig**

85 is correct 5 degrees from the vertical.
*January 29, 2016*

**physics**

since v = √(2as) v for a 1m fall is √19.2 v for a .81m bounce is √(.81*19.2) = .9√19.2 so, the c.r is 0.9 it's just the √ of the bounce-height ratio.
*January 29, 2016*

**calc 1**

do you mean (√(1+t)-√(1-t))/t ? That is indeed 0/0 "rationalizing" the numerator, we have (√(1+t)-√(1-t))(√(1+t)+√(1-t)) -------------------------------- t (√(1+t)+√(1-t)) (1+t)-(1-t) ---------------- t (√(1+t)+&#...
*January 29, 2016*

**math**

nope. 180 inches = 15 feet, not 15 yards. So, since 1 yd = 3 ft, now you can figure the yards.
*January 29, 2016*

**Limits calc 1**

nope. remember your Algebra I. (a^3+b^3) = (a+b)(a^2-ab+b^2)
*January 29, 2016*

**Math**

solve just like an equation: -15x+3 >= -3(4x-7) -15x+3 >= -12x+21 -18 >= 3x -6 >= x
*January 29, 2016*

**math**

1/x + 1/y = 1/2 I cannot parse the second sentence.
*January 29, 2016*

**Math**

well, did you plug in the values? 2(1.5)+5(1) = 3+5 = 8 6(1.5)+1 = 9+1 = 10 so, yes, that is the solution. Learn to check your answers after you figure them out.
*January 29, 2016*

**Math plz...**

no idea what you mean with -x+3, but the table has the rule y = 40-5x
*January 29, 2016*

**Math**

I assume you meant (2x-10)/5 = 3/4 4(2x-10) = 5(3) 8x-40 = 15 8x = 55 x = 55/8
*January 29, 2016*

**calc 1**

horizontal line at y=3 for 0<=x<=8 then horizontal line at y=22
*January 28, 2016*

**chemistry**

I think there is more to this problem than just an equation. Presumably, given enough TNT, you could produce as much water as you want. Though I suspect water production is not generally the purpose of the reaction ...
*January 28, 2016*

**Purdue Trig**

sounds like spherical trig to me.
*January 28, 2016*

**math**

geez, give it a rest already, willya? 10^3 * 26^2
*January 28, 2016*

**geometry**

clearly, when the longest side is the sum of the other two sides, the triangle has flattened into a line. So, 17-x = 8-x + 15-x 17-x = 23-2x x = 6 cutting off 6" leaves the lengths of 2,9,11, a flat triangle.
*January 28, 2016*

**Math**

Starting with $10, I bought 3 candy bars at 75 cents each, and 2 sodas at 50 cents each. How much money was left after the purchases?
*January 28, 2016*

**Math**

p=3s s=2m p-(x+y) = s+x p-(x+y) = m+y If p gives away 1/2 of his eggs, 1/6 to s and 1/3 to m, then Pablo has p/2 Sofia has p/3 + p/6 = p/2 Mia has p/6 + p/3 = p/2
*January 28, 2016*

**Math Help**

well, we are told that v(t) is the velocity at time t. Looks like B to me.
*January 28, 2016*

**Help Math**

exatamente correto de nada
*January 28, 2016*

**math**

37/1 -16/5 92/10 = 46/5 -23/100
*January 28, 2016*

**Algebra**

If there were x of each to start, then x = 4(x-66)
*January 28, 2016*

**writing equations-Math**

20(x-2) = 60 60/(x-2) = 20
*January 28, 2016*

**triggggg help**

well, tan = sin/cos, right? Also, 67.5° = 3pi/8 = tan(1/2 * 3pi/4) so you can use the half-angle formula tan(x/2) = sinx/(1+cosx) tan 3pi/8 = (1/√2)/(1-1/√2) = (1/√2) / (√2-1)/√2 = 1/(√2-1) = √2+1 or, √((2+√2)/(2-√...
*January 28, 2016*

**Calculus**

(√(6-x)-2)/(√(10-x)-3) (√(6-x)-2)(√(10-x)+3) ----------------------- (√(10-x)-3)(√(10-x)+3) (√(6-x)-2)(√(10-x)+3) ---------------------- 10-x-9 as x->1, that is (6√5 - 12)/±0 undefined
*January 28, 2016*

**Tips**

Once you have submitted your question, the screen will show a line like Your question, Tips, was successfully posted Click on the word Tips and your posting will open up again for your review. Proofread it and watch for typos, formatting, font problems, etc. Make sure it is ...
*January 28, 2016*

**Tips**

See tips below.
*January 28, 2016*

**Calculus**

http://www.jiskha.com/display.cgi?id=1453991598
*January 28, 2016*

**Math**

1/2 = 2^-1 32 = 2^5, so (2^-1)^(2-x) = (2^5)^(x+1) 2^(-1(2-x)) = 2^(5(x+1)) -2+x = 5x+5 4x = -7 x = -7/4
*January 28, 2016*

**intermediate algebra**

since time = distance/speed, 186/(24+x) = 102/(24-x)
*January 28, 2016*

**Math**

Draw a diagram. The line from the satellite and a city is tangent to the radius from the center of the earth. If that radius is r, then the angle θ subtended by the satellite and one city is θ = 1125/r So, if the satellite is h mi high, r/(r+h) = cosθ h = r/cos...
*January 28, 2016*

**Math**

sorry - ain't so. Check for typos However, cot(sec^-1(A)) = √(A^2-1) cot^2(sec^-1(A)) = A^2-1 I think I can see how the question was mangled. Can you?
*January 28, 2016*

**math**

take a look at the 2nd related question below.
*January 28, 2016*

**Calculus**

since p(t) is the population given time, p^-1(t) is the time needed to attain a certain population. p=7500/(1+749e^-0.15t) 1+749e^-0.15t = 7500/p 749e^-0.15t = 7500/p - 1 e^-0.15t = (7500/p - 1)/749 -0.15t = ln((7500/p - 1)/749) t = -20/3 ln((7500/p - 1)/749) or t = -20/3 ln((...
*January 28, 2016*

**maths**

(1) 1600*30 (2) 0 (3) p = mv, so dp/dt = m dv/dt = 1600*(0-30)/(20-0) = -2400 kg-m/s (4) see (3) (5) F = ma
*January 28, 2016*

**math**

start here, where the facts are written as algebra: x+y = 120 3x = 2y
*January 28, 2016*

**mathematics**

there are many good amortization calculators online.
*January 28, 2016*

**analytic geometry**

see related questions below
*January 28, 2016*

**math**

c = 5b c+2 = 3(b+2) c+2 = 3(c/5 + 2) c+2 = 3c/5 + 6 2c/5 = 4 c = 4*5/2 c = 10 Check: Carol is now 10, brother is 2 in two years, Carol is 12, brother is 4
*January 28, 2016*

**math**

Kleeneces
*January 28, 2016*

**Math**

No idea about Jean, but (3/5)/(1/9) = 27/5 or 5 2/5 as much
*January 28, 2016*

**maths**

well, start with s = rθ and then plug in your numbers θ is in radians, not degrees.
*January 28, 2016*

**maths**

since 8 mo. is 2/3 year, 2520(2/3)(r/100) = 84
*January 28, 2016*

**Maths**

since time = distance/speed, 40/x + 250/(x+20) = 3
*January 28, 2016*

**calc**

I think you must mean s(t) = e^(cos(t)) velocity is zero when v(t) = ds/dt = e^cos(t) (-sin(t)) = 0 sin(t)=0 when t is a multiple of pi. So, it looks like you are in error.
*January 28, 2016*

**Math**

I don't think you can answer the question without knowing how much the mirror had to be tilted. If the mirror is tilted an angle x, and the angle θ from the normal is formed by the ray from eye to mirror to window, then we have (if the height of the window is h): 1.82...
*January 28, 2016*

**analytic geometry**

the asymptotes are always y=±(b/a)x 2x^2 + 5y^2 - 16x + 20y + 108 =0 2x^2-16x + 5y^2+20y + 108 = 0 2(x^2-8x) + 5(y^2+4y) + 108 = 0 2(x^2-8x+16) + 5(y^2+4y+4) + 108 - 2(16) - 5(4) 2(x-4)^2 + 5(y+2)^2 + 56 = 0 I suspect a typo, since the above equation has no real ...
*January 28, 2016*

**Math**

you can multiply the 2nd equation by -5, and then you have 5x + 2y = 1 -5x + 15y = -35 Now you can easily add them to get rid of x, then find y.
*January 28, 2016*

**Calc II**

4sec(x) dy/dx = e^(y+sin(x)) 4secx dy = e^y e^sinx dx e^-y dy = 1/4 e^sinx cosx dx -e^-y = 1/4 e^sinx + c e^-y = -1/4 e^sinx + c -y = ln(c - e^sinx/4) y = -ln(c - e^sinx/4) y(0) = -5, so -5 = -ln(c - 1/4) 5 = ln(c - 1/4) e^5 = c - 1/4 c = 1/4 + e^5 y = -ln(1/4 + e^5 - e^sinx/4)
*January 28, 2016*

**analytic geometry**

y^2 = 4px has directrix x = -p focus x = p the l.r. has length 2p. No electricity is involved. the l.r. of an ellipse has length 2b^2/a recall that b^2+c^2 = a^2 and eccentricity is c/a
*January 28, 2016*

**math**

just set R(x) = C(x) and solve for x.
*January 28, 2016*

**Math**

well, you know y=10-6x so substitute that into the other equation.
*January 28, 2016*

**operating system**

LRU
*January 28, 2016*

**Math**

only two
*January 27, 2016*

**analytic geometry**

However, they wanted the acute angle. So, Sylvia, now it's up to you...
*January 27, 2016*

**Math**

(1/4 + 2/3)x + 200 = x
*January 27, 2016*

**Riddle**

man's mother's nephew is a cousin of the man cousins have the same grandparents. so, the woman's father is also the man's cousin. 2nd cousins share the same great-grandparents. So, the man and the woman are 2nd cousins, once removed.
*January 27, 2016*

**AAMU**

speed = distance/time, so (2+2)/(2/8 + 2/6) = 48/7 km/h
*January 27, 2016*

**Math**

what is the only symbol which has no definite value?
*January 27, 2016*

**math**

If you worked x hours, then sister worked 7-x hours. So, now you just have to solve 4x + 5(7-x) = 32 Plug and chug.
*January 27, 2016*

**Math**

5/3 g + 5/6 - g = 2/3 g + 5/6 or (4g+5)/6
*January 27, 2016*

**Pre-calculus**

We have a right triangle whose hypotenuse is the distance (d) between the boats: d^2 = 16t^2 + 18(t-1)^2
*January 27, 2016*

**Pre-calculus**

assuming the tank is pointed-end down, the water forms a cone, so v = π/3 r^2 h Now, using similar triangles, (r/h) = 9/16, so v = (π/3)(9/16 h)^2 h = 27π/256 h^3 h = 3/8 ∛(2πv) since this is precal, not calculus, I'm not sure what tools you have ...
*January 27, 2016*

**Math**

you are correct.
*January 27, 2016*

**math**

just add the differences to the average. Clearly the results will be in the same order as the differences.
*January 27, 2016*

**math...finding cubic feet**

well, v = πr^2 h so, plug in your numbers. Apparently the radius is 3/8 inches Then recall that it takes 1278 in^3 to make 1 ft^3.
*January 27, 2016*

**Calc 1 limits**

If you canceled out the x+3 terms, that leaves the x-3 terms, so your quotient is 1/(x-3)^2 But your answer is indeed 1/36
*January 27, 2016*

**trigonometry**

use the difference formula: sin(π-x) = sinπ cosx - cosπ sinx sinπ=0 and cosπ = -1, so you wind up with 0 - (-1)(sinx) = sinx Also, if you draw the angles in standard position, recall that sinθ = y/r cosθ = x/r since y is positive in QI and ...
*January 26, 2016*

**Math**

for the cone, the slant height s and the height h and the radius r obey s^2 = r^2+h^2 so, the height is √20=2√5 cone volume is 1/3 πr^2h = 32√5 π/3 cylinder volume is πr^2h = 102π so add them up
*January 26, 2016*

**Math**

the area of the base with diameter d is π/4 d^2 = π/4 * .5^2 = π/16 the volume is just base * height better review your formulas. Here's a good reference: http://www.regentsprep.org/regents/math/algebra/as2/solids.htm if you still have questions, or just ...
*January 26, 2016*

**Math**

no problem. Of course, telling me the front side has the line does not help, since I cannot see which face is the front.
*January 26, 2016*

**Math**

just plug the numbers into your volume formulas. The square-ish part cannot be a cube, since the sides differ in length. Must be a rectangular prism. You don't say which side has the diagonal line, but using the Pythagorean theorem to find h, if it is on the 1" side, ...
*January 26, 2016*

**Calculus**

Just keep in mind the chain rule. Every time you have a y, you will produce a y'. x^2 = (x-y)/(x+y) 2x = ((1-y')(x+y) - (x-y)(1+y'))/(x+y)^2 At this point, it's just algebra. Collect all the y' stuff on one side, and you wind up with (one form, anyway): y&#...
*January 26, 2016*

**input output**

Look at the first two terms. x increases by 8, and y increases by 12. So, clearly the rule is y=(3/2)x + ... Since (3/2)*4=6, and y=6, our rule must be just the above: y = 3/2 x So, when y=60, x=40 Fill in the blank with any convenient values: 20, 30 comes to mind.
*January 26, 2016*

**Math**

If the length is x, then 2(90+x) = 500
*January 26, 2016*