Monday
March 2, 2015

Posts by steve


Total # Posts: 29,297

algebra
aw, shucks. >scuff scuff< we aim to please, ma'am.
February 6, 2015

algebra
a^2-a-2 = (a-2)(a+1) a^2-7a+10 = (a-2)(a-5) So, the first fraction is just (a+1)/(a-5) a^2-2a-3 = (a-3)(a+1) a^2+5a+4 = (a+4)(a+1) So, the 2nd fraction is just (a-3)/(a+4) Now you have (a+1)/(a-5) - (a-3)/(a+4) putting it all over a common denominator of (a-5)(a+4), the ...
February 6, 2015

Math
1/5(2x-10) + 4x = -3(1/5x + 4) first, get rid of those pesky fractions by multiplying by 5: 2x-10 + 20x = -3(x+20) 22x-10 = -3x - 60 25x = -50 x = -2
February 6, 2015

help math
well, did you check it? 3*1+7 = 10 -11 + 2*1 = -9 Bzzzt, but thanks for playing 3x+7 = -11+2x subtract 7+2x from both sides and you have x = -18 check: 3(-18)+7 = -47 -11+2(-18) = -47 That's better. So, how did you come up with 1?
February 6, 2015

physics
R=E/I = 1.30/.665 = 1.955Ω Of that, 0.182+0.139=0.321Ω is in the batteries. So, the lamp contributes only 1.634Ω
February 6, 2015

math
multiply each average score by its weight, and add them up. quizzes: 66.25 Labs: 77.375 Now weight the scores as indicated: 0.05*66.25 + 0.20*80 + 0.20*70 + 0.15*77.375 + 0.15*85 + 0.25 * 75 = 76.42 You do it this way because if all the weights (percentages) add up to 1, then ...
February 6, 2015

math
I assume you mean sin(5/2 x) = -1/2 so, 5/2 x = 210 or 330 or 570 ... x = 84 or 132 or 228 ... We have to stop at 180, so 84 and 132 are the solutions.
February 6, 2015

Math
pretty close. I got 5.451 Double check, and keep 3 digits after the decimal point, as instructed.
February 6, 2015

IPC
v = 43 - 0.28a so, what is a if v=0?
February 6, 2015

algebra
clearly, if the line contains (0,0), x+y=0
February 6, 2015

math
If there are 4x kg of maize and 3x kg of beans, then we have 1.3(4*4/7 + 2*3/7) = $4.09/kg check: 4kg at $4 = $16 3kg at $2 = $6 4.09*7 = $28.63 = 1.3 * $22
February 6, 2015

Mathematics
aside from 6^2 + 2^6 = 10^2 I can't think of any others. My number theory skills are not sufficient for me to come up with a proof. What unit are you studying for this? It might give me a clue.
February 6, 2015

math
#4 cannot be correct y increases, then decreases, then increases again. However, if y(2) = -2, y = x^2-6 For #5, clearly (a) and (b) are out. Since 5 = 1+4, (c) must be correct, but there is a other huge typo. y(2) = 8, NOT y(7)
February 6, 2015

math
(3/5)(0.80) + (2/5)(1+p) = 1.10 p = 0.55, or 55% markup
February 6, 2015

Calculus
hmmm. you keep the details pretty close, eh?
February 6, 2015

factorization
3*5*7 = 105 now any multiple of 105 has them as prime factors.
February 6, 2015

math
y(6) = 2, so y = -2(x-6)+2 = 14-2x for 0 <= x <= 7
February 6, 2015

math
His increments each year were 0,x,2x,3x,4x, summing to 10x So, 10x = (32400-6000)/5
February 6, 2015

algebra
7x + 3x + 90 = 180 10x = 90 x = 9
February 6, 2015

math
correct does the answer i convert right? yes, but your English needs some work.
February 6, 2015

math -hw help
√3 s^2 = 3/2 s^2 = √3/2 clearly, s is not rational √3s^2 = 4√3 s^2 = 4 s = 2, a whole number. Now you try the other.
February 5, 2015

geometry
using similar triangles, 1.5/8 = FG/(32+8)
February 5, 2015

algebra
(2x+5)/(x^2+3x+2) - (x+4)/(x^2+3x+2) = (2x+5-x-4)/(x^2+3x+2) = (x+1) / (x+1)(x+2) = 1/(x+2)
February 5, 2015

calculus
y = 18/√x = 18x^(1/2) y = √(18/x) = 3√2 x^(1/2) Hard to tell what you meant, with that trailing √ sign. Do you write 2x+ to mean 2+x as well?
February 5, 2015

Trig
sinx/cosx(sinx+cosx/sinx×cosx) As written, it's sinx/cosx (sinx + (cosx/sinx) * cosx) which I doubt is what you meant. I expect you wanted (sinx/cosx)*((sinx+cosx)/(sinx*cosx)) = sec^2x (sinx+cosx) which is not secx. so, what do you really mean?
February 5, 2015

Trig
try tossing in some parentheses to make it clear just what is in the denominators...
February 5, 2015

Calculus
∫3√x (2x^2-4) dx If we let u = √x du = 1/2√x dx x = u^2 and we have ∫3√x (2x^2-4) dx ∫6x (2x^2-4) dx/2√x ∫6u^2(2u^4-4) du and that's just power stuff.
February 5, 2015

math
assuming positive integer n, n even and x negative cannot be evaluated in real numbers. As in ∜(-3) or √(-17) If we allow any real values for n, then things get more complicated. Of course, any negative power of 0 is undefined.
February 5, 2015

Calculus
the anti-derivative of the integral? You want to integrate twice? I'll just go with ∫(7tan^2x+12) dx ∫(7sec^2x-7+12) dx ∫(7sec^2x+5) dx and that's elementary, right
February 5, 2015

Calculus
(a) treat x and y as constants and you have 5x^4m^4 + y^3 (b) v' = 6t+8 v" = 6
February 5, 2015

Calculus
just divide each term by t^4 and you have 7/t^2 + 6/t^3 - 15/t^4 If that doesn't look familiar, think of it as 7t^-2 + 6t^-3 - 15t^-4 and then just apply the power rule as normal.
February 5, 2015

Calculus
f" = x^2 f' = 1/3 x^3 + c f'(0)=3, so c=3 and f' = 1/3 x^3 + 3 Now do that again going from f' to f.
February 5, 2015

College Algebra
in each case, all the 1st coordinates are the domain, and the 2nd coordinates are the range. If no element of the domain appears more than once, it is a function.
February 5, 2015

Algebra
If x is at 3%, the remainder (9000-x) is at 2.6%. So, add up the interest: .03x +.026(9000-x) = 250
February 5, 2015

Math
correct. It is a polynomial: y = -x^3
February 5, 2015

algebra
Assuming a month is 4 weeks, after x weeks, Sparky weighs 4 + (5/2)(x/4) So, when do you have 4 + 5/8 x = 14 That is the number of weeks, not months. Clearly it is linear, not exponential. (2.5 lbs/month)
February 5, 2015

Maths
a+b+c+d = 116 a+5 = b-4 = 3c = d/2 22,31,9,54
February 5, 2015

Algebra II
√-18x^5y^4 = √9x^4y^4√-2x = 3x^2y^2√2 i
February 5, 2015

Calculus
You have ∫√((x-1)/x^5) dx = ∫√((x-1)/x) 1/x^2 dx If you let u = (x-1)/x du = 1/x^2 dx and you have ∫√u du = (2/3) u^(3/2) = (2/3) ((x-1)/x)^(3/2) + C
February 5, 2015

Maths Problem
a = b+x m = b+6 a+b+m = 9x (b+x)+b+(b+6) = 9x 3b+x+6 = 9x 3b = 8x-6 b = (8x-6)/3 I guess you can finish it off now.
February 5, 2015

chemistry
PV=kT Since P is constant, V/T = k/P is constant if V is decreased by a factor of 361/400, T must decrease by the same factor to have the quotient remain constant. 298.15 * 361/400 = 269.08K It seems odd that the temperature goes down as the gas is squeezed, but remember that ...
February 5, 2015

algebra
5/(1/2 * 4/7) = 17.50
February 5, 2015

algebra
$60
February 5, 2015

math
you want the slope of the line through (-3,-4) and (-5,6) That is 10/-2 = -5 Not quite sure why the negative time values. I guess that means minutes before noon.
February 5, 2015

algebra
37 @ $1 = $37 so, there are $14 extra. That means there were 14 $2 and 23 $1 coins.
February 5, 2015

english?
yes, that's sort of like English.
February 5, 2015

math
2(w + 2w+6) = 102
February 5, 2015

math - incomplete
.
February 5, 2015

math
pi * (100/2pi)^2 = 2500/pi ft^2
February 5, 2015

math
correct, except for the spelling of phrase.
February 5, 2015

math
6(-3) = -18
February 5, 2015

math
since the angle from 240-180=60 feet away is 45 degrees, the height is 60. SO, if the angle is x, we have tan(x) = 60/240 Now just find x.
February 4, 2015

math
v(t) = 30-32t so, when is 30-32t = 10 (going up)? 30-32t = -10 (coming down)?
February 4, 2015

Survey of Calculus
That is correct.
February 4, 2015

math
must be 42
February 4, 2015

solid
CS=5, so the distance is √(25+144) = 13
February 4, 2015

math - eh?
and the answer is . . . 42
February 4, 2015

Math
Depends on the dimensions of the patio, and whether partial stones (after cutting) may be used. Just the simple answer is 24*100^2/30^2 = 267.7 stones.
February 4, 2015

Math
after h hours, you want √((18h)^2+(24h)^2) = 150 30h = 150 h = 5
February 4, 2015

math 4th grade
3 1/2 + (2+ 4 1/2) 3 1/2 + 4 1/2 + 2 3 + 1/2 + 2 + 4 + 1/2 3+2+4 + 1/2 + 1/2 9 + 1 10 or, you can rearrange the numbers in other ways.
February 4, 2015

math
If each notebook cost x, then 3x + 2*3.95 + 1.23 - 0.75 = 15.85 Now just solve for x.
February 4, 2015

Math
just start working your way from the inside out. How far do you get? for example, [(4x^2)^-1]^-2 = (4x^2)^(-1 * -2) = (4x^2)^2 = (4)^2 (x^2)^2 = 16x^4 do each factor like that and then simplify.
February 4, 2015

Calculus 2
you are correct. My bad. Good catch.
February 4, 2015

Calculus 2
∫ e^x √(1+e^(2x)) dx Note that if u = e^x, you have ∫ u√(1+u^2) du Now, if v = 1+u^2, dv = 2u du, and you have 1/2 ∫ √v dv That I think you can handle, eh?
February 4, 2015

Math
#1 x^2 = 2x-1 x = 1 #2 2(x-1) = 3x+1 x = -3
February 4, 2015

Math
(2+2+2)/2 - 2 = 1 2+2+2 - 2/2 = 5 2+2+2 + 2/2 = 7 2*2*2 + 2/2 = 9
February 4, 2015

Math
1 false a^x is exponential, for any positive a. #2 false, since 1^x is constant.
February 4, 2015

Calculus 2
(x^3+5x^2+12)/((x^2)(x^2+4)) = (x+2)/(x^2+4) + 3/x^2 So, ∫(x^3+5x^2+12)/((x^2)(x^2+4)) = ∫ (x+2)/(x^2+4) + 3/x^2 dx = 1/2 log(x^2+4) + arctan(x/2) - 3/x + C
February 4, 2015

Math
Nope. try 4n-6 < 0.5(-n) "opposite" is a vague term. Usually it means negative. You have interpreted it as reciprocal. In either case, "the product of four and a number" is 4n six less than that is 4n-6, not 6-4n.
February 4, 2015

physics
both are 3 significant digits.
February 4, 2015

Math
why divide? Just add up all the times. Dividing by 4 will give the average time per activity, but no one asked for that. Dividing 4 by the sum is meaningless. It gives the number of activities that can be done in a second, but that's of no use to anyone.
February 4, 2015

math
2/5 + 1/6 + 1/3 = 12/30 + 5/30 + 10/30 = 27/30 So, what's not covered?
February 4, 2015

Algebra
23 nickels is right, but that wasn't what you were asked to find.
February 4, 2015

From Theory to practice
Q: What's the difference between theory and practice? A: In theory, there is no difference, but in practice, there is!
February 4, 2015

algebra
(4x+6)(4x-6) = 16x^2-36
February 4, 2015

Math - Absolute Value Inequalities
B is correct. |x-2| means the difference between x and 2. That difference must be less than 3, so 2-3 < x < 2+3 -3 < x-2 < 3
February 4, 2015

math
4^2 = 16 5^2 = 25 so, 4.5 is a good first guess. 4.5^2 = 20.25 too big 4.4^2 = 19.36 4.45^2 = 19.80 4.46^2 = 19.89 4.47^2 = 19.98 4.48^2 = 20.07 So, you want something between 4.47 and 4.48 keep going.
February 4, 2015

College Alegbra
w(2w-7) = 400
February 4, 2015

trig
who is r? If x is the angle between p and q, then 12^2 = 8^2+10^2-160cos(x) Now subtract x from q's heading (not bearing!)
February 4, 2015

geometry
since the linear scale has doubled, the volume has grown by a factor of 8.
February 4, 2015

Algebra 1B
surely your text has examples and explanations. And remember that google is your friend.
February 4, 2015

algebra
for F(x) = ax^2+bx+c, the vertex lies on the axis of symmetry, at x = -b/2a. so, for your function, that is at x = -2/-2 = 1 f(1) = 7 so, the vertex is at (1,7). See the graph at http://www.wolframalpha.com/input/?i=-+x^2+%2B2x+%2B+6 Recall that the quadratic formula says that...
February 4, 2015

algebra
there are oodles of online graphing utilities. wolframalpha.com desmos.com come to mind. Just type in your function.
February 4, 2015

algebra
to find the y-intercept, set x=0: f(0) = 1 To find the x-intercept(s) use the quadratic formula.
February 4, 2015

Calculus II
use integration by parts. Let u = x, du=dx v = e^-4x dx, v = -1/4 e^-4x ∫ udv = uv - ∫v du so, ∫(x)(e^-4x dx0 = -1/4 xe^-4x + 1/4 ∫e^-4x dx = -1/4 xe^-4x - 1/16 e^-4x = -1/16 e^-4x (4x+1) + C
February 4, 2015

math
f(g) = 3g+4 = 3(bx-4)+4 = 3bx-8 g(f) = bf-4 = b(3x+4)-4 = 3bx+4b-4 Clearly, b = -1
February 3, 2015

Geometry
I get 7/2
February 3, 2015

Math - Operations with Algebraic Vectors
|i+3j-k| = √(1+9+1) = √11 Better go back to where it shows how to figure the length of a vector.
February 3, 2015

MATH
If there are n terms, n/2 (5+61) = 957 n = 29
February 3, 2015

Math
12x-6y=21 3x+6y=9 now add them up and the y's are eliminated. Should be easy going from there.
February 3, 2015

math (geometry)
42
February 3, 2015

calculus
y' = x-3 P0 = (1,4) ∆y = y'(x0)*∆x = (-2)(0.1) = -0.2 P1 = (1.1,3.8) ∆y = y'(x1)*∆x = (-1.9)(0.1) = -0.19 P2 = (1.2,3.61) ∆y = y'(x2)*∆x = (-1.8)(0.1) = -0.18 P3 = (1.3,3.43) Read the fine article at wikipedia, which shows a ...
February 3, 2015

calculus
(√(x+4)-2)/x using l'Hospital's Rule, that gives (1/(2√(x+4)))/(1) = (1/(2*2))/2 = 1/4
February 3, 2015

Math
Note that the last digit of 3^n repeats: 3,9,7,1,... 3^997 = 3^996*3, so it ends in 3 so, ...
February 3, 2015

Math Work
4(1/2)(sin(pi/3+5pi/6)-sin(pi/3-5pi/6)) Now just add the fractions and plug in the values.
February 3, 2015

geometry
the area is a = πr^2 + 2πrh So, πr^2+100πr = 3000 r^2+100r = 955 r = 8.779 So, r is about 9
February 3, 2015

Geometry
CZ extended to AB is a median. The centroid is 2/3 of the way from the vertex to the opposite side. So, you have an isosceles triangle with base=6 and altitude=6
February 3, 2015

Math
I'd use (4-1)/(1+1) = (3+1)/(3+1) Don't know why all the choices have a -2 in them, since none of the points contains a -2.
February 3, 2015

Math Help - DQ?
I interpret the instruction to use the Half-Angle formula as sin(15°) = √((1-cos30°)/2) = √((1-√3/2)/2 = √(2-√3)/2 = (√6-√2)/2 Granted, the half- and double-angle formulas are two sides of the same coin, but ...
February 3, 2015

math
If you mean f(x) = (x^2-4)/(x-2) if x<2 then since x<2, (x^2-4)/(x-2) = x+2 So, f(x) = x+2 if x < 2 ax^2-bx+3 if 2 <= x < 3 4x-a+b if x >= 3 So, as x->2-, f(x)->4 That means we must have 4a-2b+3 = 4 at x=2 9a-3b+3 = 12-a+b at x=3 a = 7/2 b = 13/2 f(x...
February 3, 2015

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>

Members