Tuesday
July 26, 2016

Posts by steve

Total # Posts: 42,098

Math
4x^2 + x + 9 = 0 the quadratic formula will provide you with the complex roots.
May 15, 2016

Math
use the pythagorean theorem.
May 15, 2016

Math
that is very bogus notation. Try rewriting it with ^ denoting a power, as x^2 = x squared And lose the combined fractions. Use parentheses to delineate the meaning. 2/3/4 might be (2/3)/4 or 2/(3/4) which are not the same.
May 15, 2016

Algebra
C is wrong. Check your +- signs during the expansion
May 15, 2016

Maths
smallest answer will come from subtracting the largest value from the smallest. So, 0 - 7654321
May 15, 2016

Prealgebra
no idea what two-ni means, but the product of 1 2/5 and b is 1 less than 2 1/2 of b can be written as (1 2/5)b = (2 1/2)b - 1 maybe you can take it from there...
May 15, 2016

calculus question ?
You are correct in both cases. Consider f(x) = 1/x and f(x) = tan(x)
May 14, 2016

math
since xy=k, a constant, you need y such that 4y = 8*24
May 14, 2016

Maths
surely you have the formulas necessary. Just plug in your numbers.
May 14, 2016

Geometry
looks good
May 14, 2016

Math
Huh??? The only one of those answers less than 4 hours is A!
May 14, 2016

Math help.
well, plug in -x+13 for y and you get -x+13 = x^2+6x+7 x^2+7x-6 = 0 This has two solutions, but they are not listed among the choices. Check for a typo.
May 14, 2016

Algebra
t^6 + t^3 - 8 = 0 now just use the quadratic formula for t^3: t^3 = (-1±√33)/2 Now you can use de Moivre's formula to get the various cube roots of those two values.
May 14, 2016

Physics
F = ma, so a = 4 m/s^2 v = at, so 8 = 4t. t=2 s s = 1/2 at^2 = 2*4 = 8 m
May 14, 2016

math
check for a typo. There are two solutions, but they are not listed.
May 14, 2016

Math
just do them step by step -x(5x-4) (-x)(5x) + (-x)(-4) ... 5k^2(-6k^2-2k+6) (5k^2)(-6k^2) + (5k^2)(-2k) + (5k^2)(6)
May 14, 2016

Algebra
to have one root, the discriminant must be zero. That is, 4+16m = 0
May 14, 2016

math (PLZ HELP ASAP)
p = 2d p+2 = 3(a+2) d = a+5 p+2 = 3(d-5+2) = 3(p/2 - 3) p+2 = 3/2 p - 9 p/2 = 11 p = 22
May 14, 2016

Math
same as the previous question. Just plug in the values and evaluate.
May 14, 2016

Math
just plug in their values: f(x)-g(x) = (3x+5) - (-x+9) now just simplify
May 14, 2016

Math calculation
how many oz per liter? multiply that by 2.5 divide that by 2.
May 14, 2016

math (pLZ HELP ASAP)
substitute t+7 for u and you get 10t + t+7 + 26 = 5(t + t+7) 11t + 33 = 10t + 35 t = 2 so, u=9 and the number is 29 check: 29+26 = 55 = 5(2+9)
May 14, 2016

math (pLZ HELP ASAP)
u = t+7 10t+u + 26 = 5(t+u) now just crank it out.
May 14, 2016

Maths
depends on the length of the wiper blade - inner and out radius. Then a = 1/2 r^2 θ
May 14, 2016

maths
greater than 96 odd with units less than tens. 97 121 71471928373 or many many others I think you have left out some information
May 14, 2016

ALGEBRA
well, 2+6 = 8, so ...
May 14, 2016

geometry
google is your friend. Try here: https://www.math.washington.edu/~king/coursedir/m444a00/syl/class/trapezoids/Trapezoids.html
May 14, 2016

Maths
.30a + .10o = .15(a+o) .15a = .05o 3a = o so as long as there are 3 times as many oranges as apples, this will work out. check: apples: 6 of 20 oranges: 6 of 60 total: 12 of 80 = 15% 30 of 100 30 of 300 60 of 400 = 15%
May 14, 2016

maths
the same (alternate interior angles)
May 14, 2016

Algebra Quadratic
you want the solution to mx-2 = x^2 to have a zero discriminant. So, since x^2 - mx + 2 = 0 has discriminant of m^2 - 8 I guess that tells you what m is, right? Take a look at http://www.wolframalpha.com/input/?i=plot+y%3Dx^2,+y%3D%E2%88%9A8+x-2,+y%3D-%E2%88%9A8+x-2
May 14, 2016

math
actually, its speed is the same. The velocity has opposite direction.
May 14, 2016

math
same as when it left. momentum is conserved.
May 14, 2016

Math
consider Mike and Fred as one person. At the table for 7, then there are 2*11P6 ways to seat them, since the 7th seat is always taken. and 5! ways to seat the others. If they do not sit at the big table, then there are 7! ways to seat that table and 2*4! ways to seat the other...
May 13, 2016

Algebra
(x+y)/2 > 0 x+y > 0 y > -x so, y can be positive or negative, depending on x. for example x = 3 y = -2 (x+y)/2 = 1/2
May 13, 2016

PLZ HELP ASAP math
p = 2d p+2 = 3(a+2) d = a+5 Now just crank it out.
May 13, 2016

Math
A The last digit must be 0 or 5, and the 1st digit is not 0, so ending in 0: 5*4*1 ending in 5: 4*4*1 B toss out all those starting with 8 or 9.
May 13, 2016

Geometry
the middle is the average of the two ends.
May 13, 2016

Geometry
you've posted a lot of these, and all you have to do is use your formulas. We can check your answers.
May 13, 2016

Geometry
clearly the base sides and the altitude will be 18, so v = 1/3 * 18^3
May 13, 2016

6th grade math
3/9 assuming that the pairs are together, so one draw get a pair. If the socks are loose and two draws are required, things are different.
May 13, 2016

Math
you can verify your work at http://www.wolframalpha.com/input/?i=%28%283x^4%29-%282%2Fy^5%29%29^9
May 13, 2016

Math
-n = 10
May 13, 2016

Math
Jen's answer was wrong in any case, but you should have used some parentheses to make things clear. All you need is a common denominator, as all the choices show. So, do what you do with normal numeric fractions: 6/(x+2) - 1/(x+9) = 6(x+9) - 1(x+2...
May 13, 2016

integration....
sorry - you cannot do ∫√(x dx) But, you can integrate √x dx since that is just x^(1/2) dx and the power rule gives you x^(3/2) -------------- = 2/3 x^(3/2) + C 3/2
May 13, 2016

Math
works for me.
May 13, 2016

Math
well, just start listing them: 7539 -> 1 78.. -> 4P2 79.. -> 4P2 8... -> 4P3 9... -> 4P3 now add 'em up.
May 13, 2016

math
well, a 12" tile covers 1 ft^2, right?
May 13, 2016

Math
just separate the variables: dy/(y+y^3) = dx then use partial fractions to integrate then plug in y(0) = 1 to find the constant.
May 13, 2016

Maths
depends on how far away the tree is.
May 13, 2016

Math
however, given the usual sloppiness online, I suspect we have 2/3 y + 4 = 12 2/3 y = 8 y = 3/2 * 8 y = 12
May 13, 2016

math
well, for any (x,y) the transformation is (x,y) -> (-x,y)
May 13, 2016

Math
"opposite" has no special meaning in math, but assuming you mean its additive inverse, that would be 13 + 1/9
May 12, 2016

Pre-Calc
the amount left in t years is 69*(1/2)^(t/12.4) so, plug in t=75 Note that that's about 6 half-lives.
May 12, 2016

Pre-Calc
you want t where e^.05t = 2
May 12, 2016

Math
maybe 9 10 38 40 40 85 lots of other vales could be used.
May 12, 2016

Geometry
clearly the height is 12, so the area is 1/2 * 6 * 12 = 36
May 12, 2016

Math, Algebra
No need to go to powers of 3, since 81 = 9^2. (9^2)^(3x+3) = 9^(2x-2) so, 6x+6 = 2x-2 x = -2
May 12, 2016

Math
x+y = 15 3y-4x = 4 now just crank it out.
May 12, 2016

Algebra
a road that is 48 meters wide? Man, that's some highway! And, after all the data, just what is the question? The volume of concrete needed?
May 12, 2016

calculus
just expand the polynomial and integrate f(x) = x^3+4x^2+3x
May 12, 2016

Differential Calculus
sorry about z. It is really found using the law of cosines z^2 = (8/5)^2 + 1^2 - 2(8/5)cosθ where θ is the angle between the hands. I'm sure you can figure that out.
May 12, 2016

Differential Calculus
with the center of the clock at (0,0), the distance z between the tips at t minutes after 12:00 is z^2 = m^2+h^2 z dz/dt = m dm/dt + h dh/dt m = 8/5 cos(π/30 t) h = cos(π/360 t) Now just plug in the numbers at t=120
May 12, 2016

Calculus
y = lnx The distance z from the origin is thus z^2 = x^2 + (lnx)^2 2z dz/dt = 2x dx/dt + 2lnx (1/x) dx/dt z dz/dt = (x+lnx/x) dx/dt at (1,e), z = √(1+e^2), so dz/dt = (1+1/1)(2)/√(1+e^2) = 4/√(1+e^2)
May 12, 2016

Math
20 the co- in cosine means sine of the complementary angle. If cos(90-A) = cos90cosA + sin90sinA = sinA
May 12, 2016

Math
You surely mean 6^(x-y) = 4, otherwise it would be trivial. 6^(x-y) = 4 6^x / 6^y = 4 6^y = 6^x/4 y log6 = log(6^x/4) y = log(6^x/4)/log6 or, if you like, y = (x log6 - log4)/log6
May 12, 2016

calculus
384000 = 30 x^1/3 y^2/3 y^-2/3 = 1/12800 x^1/3 -2/3 y^-5/3 y' = 1/38400 x^-2/3 y' = -y/25600 (y^2/x^2)^(1/3)
May 12, 2016

Math
well, w^0 = 1, so w^-2 = 1/w^2 or, w^-2/w^0 = w^(-2-0) = w^-2 = 1/w^2
May 12, 2016

math
time = distance/speed do the divisions and then subtract to find the difference
May 12, 2016

Calculus
x/(1/4) = tanθ 4 dx/dt = sec^2θ dθ/dt now just plug in your numbers. Careful with the units.
May 12, 2016

Maths
the powers of x go like this 6*12-0, 6*11-1, 6*10-2, 6*9-3, ... = 72, 65, 58, 51, ... So, the 4th term is 12C3 (x^6)^9 (1/x)^3 = 220x^51
May 12, 2016

Math/Precal
out of the 12! possible seatings, there are 2*11! which seat them together. (Think of the two as a single unit.)
May 12, 2016

Algebra
so what? You know that .6666 = 2/3, so 26.666 = 26 + 2/3 = 80/3 but you did not divide 638 by 1.5 on the right side better yet, 40x - 12(1.5x) = 638 40x - 18x = 638 ...
May 12, 2016

Algebra - Check My Work
all correct. good job.
May 12, 2016

Physics
ummm, how long is it kept there? every 2 years it decreases by 1/2.
May 12, 2016

science
find their speeds. Then you know that KE 1/2 mv^2 so, the ratio will be 3/4 (vH/vO)^2
May 12, 2016

Maths
assuming that B is a right angle, AC = √369 If angle A is a right angle, then AC=9 if neither, there's no way to find the third side, given only the other two.
May 12, 2016

Mathematics in English
google is your friend
May 12, 2016

Math
can't quite figure the kind of shape. some kind of prism? If so, just find the area of the base and multiply by the height.
May 12, 2016

Algebra
since the bottom is just √30, multiply top and bottom by √30. You then have (4√6 √30)/(√30 √30) = 4√180/30 = 24√5/30 = 4√5/5 or, you could note that √6/√30 = √(1/5) = √5/5
May 12, 2016

Math
swap variables and solve for y x = (y+4)/(2y-5) (2y-5)x = y+4 2xy-5x = y+4 (2x-1)y = 5x+4 f^-1 = y = (5x+4)/(2x-1) I'll check one way, you can at least do the other. If we let g f^-1, then f(g) = (g+4)/(2g-5) = ((5x+4)/(2x-1) + 4)/(2(5x+4)/(2x-1) - 5) = ((13x)/(2x-1))/((13...
May 12, 2016

Math
y=kx so, y/x = k, a constant. You want x such that 6/x = -18/6
May 12, 2016

Algebra
just like any other binomial. (2√5+3√7)^2 = (2√5+3√7)(2√5+3√7) = (2√5)^2 + 2(2√5)(3√7) + (3√7)^2 = 20 + 12√35 + 63 = 83 + 12√35
May 12, 2016

Math/Precal
there are 7 letters, so there are 7P3 = 210 ways to choose 3 of them. But the two O's are indistinguishable, so there are only 7P3/2! = 105 unique words
May 12, 2016

Math
The mistake was in starting with 9n and the saying 9n^2. 9n=3(nP2) =>9n=3(n*(n-1)) =>9n=3n^2-3n =>3n^2-12n = 0 => 3n(n-4) = 0 => n = 0,4
May 12, 2016

Math
base area = 9^2 = 81 each face has area 9*18 = 162 now just multiply each area by its cost and add up the proper number of faces.
May 12, 2016

Math
A rectangular prism is 18 inches tall and has a square base whose length is 9 inches. Oliver plans to cover the top and bottom of the rectangular prism with material A, which costs 2 cents per square inch. He then plans to cover the other four faces of the prism with material ...
May 12, 2016

math
Assuming one pole has height 6 and the other has height 11, then the distance between their tops is just √(12^2+5^2) = 13 meters
May 12, 2016

energy,power,wurk
GPE = mgh it is all KE just before impact.
May 12, 2016

calculus
find the max of f(x) = x*p(x)-c(x) = x(300-x)-(20000+24x+1/2 x^2) = -3/2 x^2 + 276x - 20000 f' = -3x + 276 f'=0 at x=92 since f" < 0, that is a max.
May 12, 2016

Pre Calculus
there are many good calculators for this online.
May 12, 2016

Math
here are the graphs. Compare them. http://www.wolframalpha.com/input/?i=plot+y+%3D+-0.7%2Fx,+y%3D-0.9%2Fx
May 12, 2016

math
c = 2πr a = πr^2 so, plug in various values for r: r c a 1 2π π 2 4π 4π ... 16 32π 256π when 2r is substituted for r, you have new values for c and a: 2π(2r) and π(2r)^2 compare those to the original values using just r.
May 12, 2016

Functions
correct
May 12, 2016

Functions
clearly, R3 = R1+R2
May 12, 2016

Functions
15% loss means each year the value is 0.85 what it was.
May 12, 2016

math
a point (x,y) on the ellipse is (x,(1/5)√(225-9x^2)) halfway there is (x/2,(1/10)√(225-9x^2)) x^2/4 + y^2/b^2 = 1 x^2/4 + (225-9x^2)/100b^2 = 1 25b^2x^2/4 + 225-9x^2 = 100b^2 (25b^2/4 - 9)x^2 = 100b^2-225 25b^2/4 = =9 b^2 = 36/25 x^2/4 + (25/36)y^2 = 1 9x^2 + 25y^2...
May 12, 2016

calculus 1
as before, but with washers v = ∫[0,2] π(R^2-r^2) dx where R=6 and r=y+2=.25x^4+2
May 11, 2016

calculus
inverse trig functions are nasty, so we will try to use dx in both cases. around the x-axis use discs (washers) of thickness dx, v = ∫[0,2π] πr^2 dx where r = 3+sinx v = ∫[0,2π] π(3+sinx)^2 dx around the y-axis, use shells of thickness dx v = &#...
May 11, 2016

Math
since 40=2^3*5, the other number must be 2^3=8 no other primes or higher powers of 2 and 5 works.
May 11, 2016

Math
42
May 11, 2016

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