Sunday

May 29, 2016
Total # Posts: 40,873

**Pre calculus**

you need to add/subtract rows and their multiples so the resulting matrix consists of a diagonal of 1's. To start, subtract R1 from R2: x + y + z = -5 0 - 2y + 2z = 4 4x + y + z = -2 Now subtract 4*R1 from R3: x + y + z = -5 0 - 2y + 2z = 4 0 - 3y - 3z = 18 Now work on the...
*May 29, 2016*

**Math**

tan(A) = (25-1.5)/23.5
*May 28, 2016*

**math**

The sum-to-product formulas might be helpful here. I think you'll find that the imaginary part is zero.
*May 28, 2016*

**algebra 2**

If the downstream rate is x, then since time = distance/speed, 75.5/x + 75.5/(x-5) = 15
*May 28, 2016*

**maths**

add up the x- and y-components of the vectors, then convert the result back to distance and bearing.
*May 28, 2016*

**Algebra**

this does not factor. The discriminant is negative. b^2-4ac = 36-4*9*8 = -252 The quadratic has two complex roots.
*May 28, 2016*

**Algebra**

notice the coefficients are all 2 or 1. So, I'd try 2x^3y^3-x^2y^3 + 2x-y x^2y^3 (2x-1) + 2x-y (x^2y^3+1)(2x-y)
*May 28, 2016*

**Math**

That would be (6.3/9) * (10^6/10^2) = 0.7 * 10^4 = 7.0 * 10^3 = 7000
*May 28, 2016*

**Math**

5(4-y) = 5*4 - 5*y = 20 - 5y
*May 28, 2016*

**Algebra**

1/a + 1/m + 1/z = 1/2 so, 1/5 + 1/6 + 1/z = 1/2 1/z = 2/15 1/a + 1/z = 1/5 + 2/15 = 1/3 so, Ann and Zack take 3 hours to do the job together.
*May 28, 2016*

**math**

original fraction is n/d (n-5)/(d-3) = 1/2 (n/2)/(d+7) = 1/4 Solving these gives n = (d+7)/2, not a single unique solution. Naturally, d cannot be 3, but it is odd, and n must be even, so we can have original fractions of 6/5, 8/9, 10/13, ... or, in general, (2k+4)/(4k+1) for ...
*May 28, 2016*

**Calculus**

You should probably solve for y using the quadratic formula. It comes out y = √(2x^3+11) - 1
*May 27, 2016*

**Calculus**

http://www.wolframalpha.com/input/?i=%E2%88%AB[1,4]+%CF%80%2825-%285-1%2Fx%29^2%29+dx Did you use ln(x)? If you used base 10, that would be wrong. As you get along in math, you will find the serious folks use log(x) to mean ln(x). It's kind of confusing if you're not ...
*May 27, 2016*

**Calculus**

y = 1/x, the x-axis, and the lines x = 1 and x = 4 is rotated about: a) the x-axis: just treat the volume as a stack of thin discs, each of area πr^2, where r=y. So, v = ∫[1,4] π(1/x)^2 dx = 3π/4 = 2.35 rotating about the line y=5, you have to use washers...
*May 27, 2016*

**Pre-Algebra (Check my answers)**

Sorry. #1 was correct for 5*3^n
*May 27, 2016*

**Pre-Algebra (Check my answers)**

as shown, the table does indeed not represent a linear function. If the 8 was a typo and you meant 9, then y = 8x+9
*May 27, 2016*

**Pre-Algebra (Check my answers)**

try using 3^n instead of 3n, which looks like multiplication. |-1| = 1, so f(2) = 2*1*2 = 4 If you actually meant (-1)^x, then f(2) = 2*(-1)^2 = 2*1 = 2
*May 27, 2016*

**Math Help Please? (check my work?)**

#1 Why do you start adding 10 each time, when the sequence clearly did not? Try adding 9 instead. #2 ok
*May 27, 2016*

**Algebra - oops**

oops. I forgot to carry the denominator along. a/bc - 2b^2/ac - 4c^3/ab
*May 27, 2016*

**Algebra**

why all the words? That's what math symbols are for. 2a^2 - 4b^3 - 8c^4 ------------------------ = a-2b^2-4c^3 2abc
*May 27, 2016*

**Calculus**

What do you mean by "finding" x,y,z? (x-2)/-1 = (y-5)/5 = (z-7)/7 or x = 2-t y = 5+5t z = 7+7t When x = -3, t=5, so the line passes through (-3,30,42)
*May 27, 2016*

**algebra**

I understand csc(A) but have no idea what the Y6 is supposed to mean. If the Y is a typo, then I suppose you could have meant 3csc(A)-6=0 csc(A) = 2 or, if you prefer, sin(A) = 1/2 A = pi/6 or 5pi/6
*May 27, 2016*

**math**

C cannot be right, since it only has two terms. Take another stab at it and see whether you can come up with (A)
*May 27, 2016*

**math PsyDAG**

well, 1.1*3 = 3.3 so A and B are clearly wrong. when multiplying, add the powers.
*May 27, 2016*

**Geometry**

good work
*May 27, 2016*

**MATH - CALC**

f = x^3-3x^2 = x^2(x-3) f' = 3x^2-6x = 3x(x-2) f" = 6x-6 = 6(x-1) Now just apply the features you know: f=0: x-intercepts x=0: y-intercept f'=0 ==> critical point f"=0 ==> inflection f'>0 ==> increasing f">0 ==> concave up
*May 27, 2016*

**math plz help**

let's do the math in base 10. 325 = 1710 1314 = 2910 x+y+z = 3*17 = 51 x+y = 29 now you can get z, and convert to base 6.
*May 27, 2016*

**math**

well, the apothem is 1/2 as long as a side, right? doesn't matter whether it's inscribed in a circle.
*May 27, 2016*

**math**

75/.06
*May 27, 2016*

**math**

cost = 2400/12*15 revenue = 1350*4 + (2400-1350)/5*8 % gain or loss = ((revenue-cost)/cost - 1)*100
*May 27, 2016*

**maths**

whoa - too many = signs!
*May 26, 2016*

**math**

by now I'm sure you have figured out what it means to substitute a value, but just in case, that gives you 15+9d = 69 Now you can get d, and thus a+3d.
*May 26, 2016*

**Calculus**

dy/dx = √[(x^3)(y)] dy/dx = x^(3/2) y^(1/2) y^(-1/2) dy = x^(3/2) dx y^(1/2) = 1/5 x^(5/2) + c Now if you square both sides, you do not get x^5/25 + c, since (a+b) is not a^2+b^2 But proceeding to find c, √2 = 1/5 + c c = √2 - 1/5 Now square both sides and ...
*May 26, 2016*

**Math**

just see which pair of values does not work. replace x and y with the values given: -4(-9)-9 = 36-9 = 27 so it is a solution now try the others.
*May 26, 2016*

**Math**

f" < 0 indicates it is concave down. f' > 0 means that the graph is rising. So, an example would be a parabola which opens downward. So, the tangent line at x=0 will be above the curve. draw a graph and it should be clear now.
*May 26, 2016*

**Calculus**

right on
*May 26, 2016*

**calc**

I find it easier to leave the π in the answer. That way it's exact, instead of some decimal approximation. In any case, I got (a) 20π/9 (b) 125π/27 #2 27π/2
*May 26, 2016*

**calc**

#1 (a) discs ∫[0,5] π((5-y)/3)^2 dy (a) shells ∫[0,5/3] 2πx(5-3x) dx (b) shells ∫[0,5] 2π(6-y)(5-y)/3 dy #2 discs ∫[0,9/4] π(((3+√(9-4x))/2)^2-(((3-√(9-4x)))/2)^2) dx shells ∫[0,3] 2πy(3y-y^2) dy
*May 26, 2016*

**Math**

draw a side view. r^2 = 6^2 + 4^2 A = 4pi r^2
*May 26, 2016*

**Math**

Recall Euler's Formula: V+F-E=2 and check out https://en.wikipedia.org/wiki/Icosidodecahedron
*May 26, 2016*

**Math-Calc**

f = 6x(3-2x)^3 f' = 6(3-8x)(3-2x)^2 f(1) = 6 f'(1) = -30 so, the tangent line is y-6 = -30(x-1) see at http://www.wolframalpha.com/input/?i=plot+y%3D6x%283-2x%29^3,+y%3D-30x%2B36
*May 26, 2016*

**Math topic help**

well, your answer is the balance after about 15.6 years, so I suspect it's not right. What did you intend?
*May 26, 2016*

**Math (Vectors)**

looks good to me.
*May 26, 2016*

**Math (Vectors)**

if they are parallel, then the lengths will be proportional. 10/2 = 5, so the ratios of the other dimensions will also be 5:1
*May 26, 2016*

**Algebra II**

No, I didn't answer the question, but I gave you enough information so you could complete the solution. Sorry to be jerk-ish.
*May 26, 2016*

**Algebra II**

So, with the triangle drawn as you have said, with the right angle on the x-axis, you just have a scaled up 3-4-5 triangle, with sides 15,20,25. sinX = 15/25 = 3/5 cosX = 20/25 = 4/5 tanX = 15/20 = 3/4 Looks like time to review your basic trig functions and the Pythagorean ...
*May 26, 2016*

**College Algebra/Drug Calculations**

just multiply numerators and denominators 5/6 * 2/3 = (5*2)/(6*3) = 10/18 = 5/9
*May 26, 2016*

**Calc-Math**

just look up the values on the graph and multiply or divide the numbers.
*May 26, 2016*

**maths-word problem**

if the digits are t and u, then 10t+u = 6(t+u)-1 t-u = 1 Looks like 65 to me.
*May 26, 2016*

**maths**

the opposite side is √(y^2-x^2) so csc(Ø) = y/√(y^2-x^2)
*May 26, 2016*

**calculus-again frustrated-looking for steve asap**

sinh(y)=[(4sinh(x)-3)/(4+3sinh(x))] cosh(y) y' = (25cosh(x))/(4+3sinh(x))^2 cosh^2(y) = 1+sinh^2(y) = 25cosh^2(x)/(4+3sinh(x))^2 so, cosh(y) = 5cosh(x)/(4+3sinh(x)) y' = 5/(4+3sinh(x))
*May 26, 2016*

**calculus-help me sir~steve**

L{f'(t)} = sF(s)-f(0) L{f"(t)} = s^2 F(s) - sf(0) - f'(0) Not sure what to do with f(0)=f'(0) since you don't give a value. L{sin(t)-cos(t)} = (1-s)/(1+s^2) Just plug in the expressions and it will all fall out.
*May 26, 2016*

**Math**

clearly, 26 * 1.5
*May 26, 2016*

**math**

75/.06
*May 26, 2016*

**Math**

2^6 = 64
*May 26, 2016*

**maths**

If the distance on the ground is x, and the height of the pole is h, h cot40° - h cot60° = 15 x/h = cot60°
*May 26, 2016*

**Saint Hilary**

1 1/2 = 3/2 1 = 2/2 (2/2)/(3/2) = 2/3
*May 26, 2016*

**math**

figure the probability of each event, then just multiply them together
*May 25, 2016*

**Math**

clearly, the size is 800 in^3 The cylinder could be short and wide or tall and thin.
*May 25, 2016*

**math**

a=15 a+9d=69 so, find d, and then T4 = a+3d
*May 25, 2016*

**math**

try that again. The fractions add up to too much.
*May 25, 2016*

**math**

well, the scale is clearly 6in : 3 ft = 2in:1ft surely you know how to figure perimeter and area
*May 25, 2016*

**math**

just divide the miles by the minutes
*May 25, 2016*

**math**

think of the six faces: top and bottom two pairs of rectangular sides
*May 25, 2016*

**math**

convert to rectangular form add up the x- and y-components convert back to magnitude and direction
*May 25, 2016*

**math**

only one, since 6^2 + 8^2 = 10^2
*May 25, 2016*

**Math**

1.48 * 250 = ?
*May 25, 2016*

**math**

well, add them up and you have 15x+14 = 180
*May 25, 2016*

**math**

both the sum of the equations ??
*May 25, 2016*

**Pre-Cal**

set u = x^(2/3) then you have u^2-9u+14 = 0 (u-2)(u-7) = 0 so, that means x^(2/3) = 2 x^(2/3) = 7 I expect you can handle that, now...
*May 25, 2016*

**Pre-Cal**

pre-cal? Try Algebra I (ax+b)/(cx+d) = 6 ax+b = 6(cx+d) ax+b = 6cx+6d ax-6cx = 6d-b (a-6c)x = 6d-b x = (6d-b)/(a-6c)
*May 25, 2016*

**Algebra II**

it's a right triangle so use the Pythagorean Theorem. If the other leg is x, then (5√3)^2 + x^2 = (x+2)^2
*May 25, 2016*

**math-need sir-steve badly asap**

well, just use the definition. F(s) = ∫ e^(-st) f(t) dt multiply that by e^(kt) and you now have ∫ e^(-(s-k)t) f(t) dt
*May 25, 2016*

**Math**

2x^2+6x-7x+8-3x^2+1 2x^2-3x^2 + 6x-7x + 8+1 -x^2-x+9 4x^2+3x-3 4,3,-3 Typo somewhere (7x^2-x-2)-(6x^3+3) 7x^2-x-2-6x^3-3 -6x^3+7x^2-x-5 6t-2 + 9t-6 15t-8 (1.4*10^1)(8*10^4) (1.4*8)* (10^1*10^4) 11.2 * 10^5 1.12 * 10^6 #18C ok 4k^2(-3k^2-4k+5) 4k^2(-3k^2) + 4k^2(-4k) + 4k^2(5...
*May 25, 2016*

**Math**

#7 has a typo. Either A or B would work, depending on what it was. No ideas on any of the others?
*May 25, 2016*

**Algebra II**

surely you know (a) what a reciprocal is (b) what a sum is (c) what consecutive integers are So, if the smaller integer is x, the equation is just 1/x + 1/(x+1) = 17/12 Unfortunately, I detect a typo. Fix it, and it will come out a lot better.
*May 25, 2016*

**Math**

can't tell when no function is given.
*May 25, 2016*

**math**

you know all three angles, so use the law of sines to find the ratio of the sides. Then just pick lengths that add to 12.5
*May 25, 2016*

**math**

either that, or "pitcher" is the wrong word to use. In any case, just add the two numbers. Since you want the answer in "simplest form," I suspect Ms. Sue is right, and you have garbled your fractions.
*May 25, 2016*

**Math/ ratios/ Fractions/ Singapore Math**

h+r = 60 (3/4 h)/(r-5) = 1/2 now just find h and r. Not sure just what the question is asking. More than when he ended, or more than Holly?
*May 25, 2016*

**physics**

just solve (39.2 sin 30°)t - 1/2 gt^2 = 14.7 You haven't specified the units, so I don't know what value g has.
*May 25, 2016*

**Math**

3x - x = 34
*May 25, 2016*

**Pre-Calc**

correct
*May 25, 2016*

**math**

naturally, that would be 16 * 1.15 * 100/12
*May 25, 2016*

**math**

original fraction: (d-6)/d adding 2, we have (d-4)/(d+2) = 3/5 ...
*May 25, 2016*

**Maths**

there are some good online calculators for this
*May 25, 2016*

**math**

.35 * 475 = ?
*May 24, 2016*

**Math-Calc**

Draw a side-view diagram. If the water is at depth y, then the surface of the water has radius 325/800 y. Thus the volume is v = 1/3 pi (325/800 y)^2 y = 0.1729 y^3 dv/dt = 0.5187 y^2 dy/dt Now just plug in your numbers. If water is being pumped in at c cm^3/min, then c-14000...
*May 24, 2016*

**geometry**

they are equal, but not necessarily the same as the other two distances.
*May 24, 2016*

**Math**

well, shoot. Look from the side. Draw a sloping line representing the ground. Place a vertical line on the slope somewhere. Label the top T and the bottom B. That is the pole. Label its length 20. Mark two points on the slope, equal distances from the pole. Label those ...
*May 24, 2016*

**math**

Since A = WL, L=A/W x^3y^4 / x^2y = xy^3
*May 24, 2016*

**simultaneous-equation help am despirate**

2x+y-z=8 x^2-y^2+2z^2=14 3x^3+4y^3+z^3=195 See whether it helps to rewrite it like this x+y + x-z = 8 z^2+x^2 + z^2-y^2 = 14 4(x^3+y^3) + z^3-x^3 = 195
*May 24, 2016*

**Algebra**

2*41 + 8x = 7(41+x) it's going to take a lot of $8 nuts to bring the price up to $7/lb from $2/lb.
*May 24, 2016*

**maths**

well, 5% of 31348 is 1567.4 That leaves her 3084.6 feet to go. And as you know, time = distance/speed
*May 24, 2016*

**Pre-Calc**

that is correct. There is a hole in the graph at x=4, because there f(x) = 0/0 which is undefined. f(x) = 1/x everywhere except at x=4.
*May 24, 2016*

**Precal/math**

you have to find g(0). Then use that value to evaluate f.
*May 24, 2016*

**algebra**

recall that (a-b)(a+b) = a^2-b^2 (x+3)/(√2-3x) * (√2+3x)/(√2+3x) = (x+3)(√2+3x)/(2-9x^2) or something, depending on whether you were sloppy with your parentheses.
*May 24, 2016*

**Calculus**

how advanced is "advanced"? trig substitution? polynomial roots? try and meet us halfway here. Surely your text has examples where u has been substituted for some expression. Do something similar. Then tweak some constant so the answer comes out 6.
*May 24, 2016*

**math**

sec(θ)/(csc(θ)-cot(θ)) - sec(θ)/(csc(θ)+cot(θ)) becomes sec(θ)(csc(θ)+cot(θ)) - sec(θ)(csc(θ)-cot(θ)) ---------------------------------------------------------- (csc(θ)-cot(θ))(csc(θ)+cot(θ)) Now ...
*May 24, 2016*

**MATHS**

24.5*13*4 * 7.48 * 0.80
*May 24, 2016*