# Posts by steve

Total # Posts: 52,265

Math
If there are x cars and y yellow cars, clearly the new car is yellow, since 1/9 > 1/10 y = x/10 y+1 = (x+1)/9 There are now 81 cars, with 9 yellow.

trigonometry
draw the diagram, and it is clear that the distance x is x/100 = tan 50°11'10"

Math
c+d = 500 .75c + .50d = 275

math
so, you used 304 ft of fence.

Math, factoring
Divide by (x^2-x-6) and you get quotient: x^2+(a+1)x+(2a+7) remainder: (8a+24)x + b+6(2a+7) For the remainder to be zero, we need a = -3 b = -6 So, x^4-3x^3-3x^2+11x-6 = (x+2)(x-3)(x^2-2x+1) The other roots are 1,1

Algebra
multiply the 2nd equation by 12 and you have 12y = -3x+20 or 3x+12y = 20 so, the two equations are the same.

Math (Double checking trig identity)
Nope. my bad. Still you were also wrong (a^2sec?)^2 - (a^2)^2 = a^4 (sec^2?-1) = a^4 tan^2?

Math (Double checking trig identity)
not at all. (a^2sec?)^2 - (a^2)^2 = a^4 (sec^4? - 1) = a^4 (sec^2?-1)(sec^2?+1) = a^4 tan^2? (sec^2?+1)

Cornhole
if you want names, puntarelli pamela kathryn huckaby

Math
No, ?35 is a number like any other, so it has to be included Just as 20+10x is not 30x, 20 + 10?35 is not 30?35 20?35 + 10?35 = 30?35 20+10?35 = 10(2+?35)

math
c'mon -- just start plugging in values for n: n=1: 1(1-2)-3 = -4 n=2: 2(2-2)-3 = -3 n=3: 3(3-2)-3 = ... and so on

Science physics
work is in Joules 2.0kg * 9.8 m/s^2 * 4.5m = 88.2 kg-m/s^2 = 88.2N-m = 88.2J work = force * distance force = mass * acceleration

Science physics
The acceleration is due to gravity g = 9.8 m/s^2

Math
correct

Math
since the ratio of height:shadow is the same, h/5 = 2/3

math
draw the two circles, and a line through their centers. Label the radii, and it should be clear what the two distances are.

maths
not sure just what you want to do with this log 5 = 0.699 I guess you can take it from there.

Math
(3 3/4)/3 = 1 1/4 Just divide everything by 3

Algebra
If the ... indicates some set of repeating digits, the number is rational If not repeating, then it is irrational Either way, it is real

Math-age problem
f+g = 60 f+6 = 2(g+6)

Math
j = e+5 j-3 + e-3 = 17 now just find 21-j

Math
those numbers are all volumes. You need to find pairs of numbers. The sum of their products is the area. Better yet, study the net to see which vertices of the prism are represented; then use what you know about prisms to get the area.

algebra
nope. the area will be 1/13^2 as much.

algebra
correct

math
2/3 as many men, so 3/2 as much time.

algebra
no, it will grow by a factor of 4^2 = 16

Algebra
just divide term by term, using the distributive property: (4x³ + 10x² + 3a) ÷ 2x² = 4x³÷2x² + 10x²÷2x² + 3a÷2x² = 2x + 5 + 3a÷2x²

Math
since east is +x and south is -y (-10,6)+(3,-12) = (-7,-6)

precal
No. If you want to find the probability that the marble you drew is blue or green, then that is just the 2/9, since 2 of the 9 marbles are either blue or green. If you mean that after the 1st marble was drawn and not replaced, what is the chance of then drawing a blue or green...

Calculus
you can do this as shells or washers. with shells of thickness dy, remember that the volume of a shell is 2?rh. So, draw the region, and ?[0,2] 2?rh dy For discs with holes, of thickness dx, work with ?[1,2] ?(R^2-r^2) dx your job is to examine the region in question and ...

physics
see related questions below

Math
see related questions below

Science
Just add up the displacements and see where you end up. The final displacement is just minus that location. For example, 50m in the direction 30degree west of north is <-50sin30°,50cos30°> = <-25.0,43.3>

algebra2
Find the sum of the following series. 14/n-=1 (2n+1)

Algebra2
What is the 50th term of the sequence that begins -2,4,10,16? My answer is 292

math
correct.

Functions
well, (fg)(x) = f(x)*g(x) = (x^2+3)(2x+a) expand that out and equate it to 4x^2-8x+7. The coefficients must all match. That will give you the value of a. Better check for typos, since fg = 2x^2 + ... and there's no way to match that with 4x^2+...

Physics
you know that with initial velocity v, s = vt + 1/2 at^2 Now just find s(10)-s(0) and s(20)-s(10) to find a and v.

Precalculus
C(x) = 396x + 12320 The price must depend on x if there is a maximum (P is a quadratic), so let's say it is 452-kx. R(x) = x(452-kx) = 452x - kx^2 P(x) = R(x)-C(x) = -kx^2 + 56x - 12330 Without some further data, I cannot say what is the value of k.

Math
what is 20% of 50?

Algebra
since 33% are girls, and 50% have black hair, some boys have black hair.

Math
if we set the center of the base at (0,0) then the parabola is modeled by the equation y = 5/2 - 5/18 x^2 Solve for x when y=2, and the beam has length 2x.

math
9!

maths --plse help me..
Hmm. I got 6 and 9 Better read the problem again. You got your division backwards: the greater divides the sum.

maths --plse help me..
If x < y, then we have (x+y)/(y+1) = 3/2 (y-x)/x = 1/2 Now just solve for x and y

Science
well 18g of steam is 1 mole of H2O So, write the balanced equation to see how many moles of Fe will be used. Then get the mass from that.

math
the girls walks on a heading, not a bearing. B's bearing from A is 78° If A is at (0,0), then B is at (279,59) If we mark point D due east of A, on the line BC, then D is at (279,0) Now, if angle DAC is ?, then cos? = 279/307 ? = 25° So, A's bearing from C is ...

math
use the law of sines. The distance z is z/sin91 = 4/sin44

MMATH08
well, since the 10 tiles cover the floor, each must have area 8000/10 = 800m^2 so, the tiles must have side length 20?2 unfortunately, you cannot cover a square floor with 10 square tiles, since 10 is not a perfect square.

Msth
just subtract the picture area from the total: (20)(30)-(20-10)(30-10)

Geometry
(x,y) -> (x-4,y-8)

Kaylee - banned
lim n->? of n ? (5+k(2/n))10(2/n) k=1

Probability and Statistics
If you plug some of your numbers in at this web site, I think you'll soon see how things work. http://davidmlane.com/hyperstat/z_table.html

Trig
not bad, but why did you subtract? d/dx (x+8)^(1/2) = (1/2)(x+8)^(-1/2) your derivative is good, except for that.

Math
to find r, note that a9/a4 = r^5 then use that to find a1

math
nope. P(heads) = 1/2 P(n<5) = 4/6 = 2/3 so, P(heads, n<5) = 1/2 * 2/3 = 1/3

Algebra
well, I guess you know the answer, then, right?

Algebra
none. You need two factors of 24 which differ by 1. Check for typos 1,24 gives 23q 2,12 gives 10q 3,8 gives 5q 4,6 gives 2q

algebra
2^(3/4) ----------- = 2^(3/4 - 1/2) = 2^(1/4) 2^(1/2)

Music
I guess you have picked the best answer Unlike a piano, whose strings are hit with hammers, and whose volume can vary (piano-forte), a harpsichord's strings are plucked (like a harp's) and always play at the same volume. Listen to some recordings and it's easy to ...

English
could is the past tense of can I can swim well. Yesterday I could swim well. Then there are the conditional and perfect uses, but maybe you're not after those.

physics
watch the units wavelength(m) = speed(m/s) / frequency(1/s)

Math (Calculus II) (Partial Fraction Decomposition
So, you have two polynomials, which are identical. That means all the coefficients on both sides must be the same. That is, x = B(x^2+a^2)(x-a) + C(x+a)(x^2+a^2) + (Dx+E)(x+a)(x-a) = B(x^3-ax^2+a^2x-a^3) + C(x^3+ax^2+a^2x+a^3) + D(x^3-a^2x) + E(x^2-a^2) = (B+C+D)x^3 + (-aB+aC+...

Math
They all look ok to me, except #2. Recall that the slope is ?y/?x pick any two pairs and see what you get #3. Note that y increases by 5 for each step. You could not possibly have tried 3x+6 on more than one pair. #5. Again, you clearly only tried n=1.

Math
No. There were 10 tosses. 8 of them showed at least one H So, P = 8/10 = 0.8

Math
you have it exactly backwards. 0.2 is the probability that NO heads showed.

Physical Science
well, 1/16 = 1/2^4 so it takes 4 half-lives

Math
16

Math
6":18' = 1:36

math - try again
fix the typos and post it again.

math
each man does 1/(24x) in a day each woman does 1/(32(x+8)) in a day so, 15/(24x) ------------ = 3/1 12/(32(x+8)) yes, x=10

science

math
42

Math
well, tan? = 180/215

Algebra 2
that's right.

Algebra 2
nope. If it has a maximum, then the graph turns back on itself, so it fails the horizontal-line test.

Geometry
Since they share a common diagonal BD, they are the same rectangle.

Algebra 2
f?g = f(g) = g^2-5g+6 = (x+3)^2-5(x+3)+6 = x^2+x

Pre Algebra
7^5 * 7^6 = 7*7*7*7*7 * 7*7*7*7*7*7 = 7^11 all 7's, no 49's

Pre Algebra
nope 7^5 * 7^6 = 7^(5+6) = 7^11 Better review the rules of exponents. The base does not change: a^m * a^n = a^(m+n) NOT (a^2)^(m+n)

Algebra 2
f(x)-g(x) = (x^2+2x-6)-(3x^2-5x-7) = x^2+2x-6-3x^2+5x+7 = -2x^2+7x+1 watch those minus signs when subtracting!

Math Graphing
http://www.wolframalpha.com/input/?i=y%3D+1%2F5x+-+2

Math
you are

Trig help
A is correct

for the integral, there are two ways. shells of thickness dx: v = ?[0,2] 2?rh dx where r = 5-x and h=x-x^2/2 v = ?[0,2] 2?(5-x)(x-x^2/2) dx = 16?/3 discs (washers) of thickness dy: v = ?[0,2] ?(R^2-r^2) dy where R=5-y and r=5-?(2y) v = ?[0,2] ?((5-y)^2-(5-?(2y))^2) dy = 16?/3 ...

maths
correct

maths
If you let u = 4x^2 v = 3-x then you have y = (u/v)^3 y' = 3(u/v)^2 (u/v)' = 3(u/v)^2 ((u'v-uv')/v^2) = 192x^5(6-x) / (3-x)^4

maths
All the steps in your work are correct.

maths - try again
all that duplicated text is impossible to parse. Try typing it in, rather than copy/pasting. Use t^2 for t squared

Trig help
C is correct

Algebra
come on. For #5, you have 5x-20y=60 5x-20y=60 They are the same equation. So, any solution to one is also a solution to the other. Try a similar comparison for #6 and just think about what it means.

math help?!
correct

algebra
15 < 5x

Science
correct

AMth
64/256 = 1/4 I don't see any matches

calculus
The sequence can be rearranged as 1/3, 1/4, 1/5, 1/6, ... ....1, 1/2, 1/3, 1/4, ... so, the terms converge to zero The sum, however, will come close to twice the sum of the harmonic series, which diverges.

calculus
2+3+4+... = n(n+1)/2 - 1 So, if N = n(n+1)/2 - 1, you know that the Nth term is 4, and the n+1st term is 0 So, while the number of zeros is infinitely many more than the number of 4's, the terms do not converge to either 4 or 0.

calculus
by this time you should know that exponentials always overcome polynomials.

calculus
since cos(x) oscillates between 1 and -1, the sequence does not converge. As n/8 comes arbitrarily close to multiples of pi, cos(n/8) will get close to 1 or -1.

calculus
since the terms are just basically 1/?n the sequence converges to 0