# Posts by Steve

Total # Posts: 51,146

math 8
yes. That is how binary numbers are formed.

Math
?r^2 = 120 so, solve for r.

precalc
(a) 3-hr factor is 0.41 m^3 = 0.41 (b)m = 0.743 (c) m^6 = 0.41^2 = 0.168 (d) 15min = 1/4 hr, so that is m^(1/4) = 0.928

Math 120
Of the 6 outcomes, 2 are not greater than 2. So, the odds are 2:4 = 1:2

Science
(75*9.8)(5.12*0.2)/5

Precalculus
a little synthetic division yields factors of (x-2)(x+6) so, divide that out and you are left with (x^2+2)

Math
well, at 3:00 they form a right angle...

Pre-cal
as always, draw a diagram. Then it should be clear that the distance is 500 cot32° + 500 cot23°

Math
I assume your two equations are y = 4x+8 y = x^2+7x-20 So, just set them equal: x^2+7x-20 = 4x+8 x^2+3x-28 = 0 (x+7)(x-4) = 0 x = -7 or 4 See http://www.wolframalpha.com/input/?i=x%5E2%2B7x-20+%3D+4x%2B8

math
2 cups = 8/4 cups That is 11/4 = 11/8 * 2 So, you will need 11/8 as much milk. 11/8 * 3/4 = 33/32 cups milk. Or, 1 cup + 1/2 tbsp.

Math - typo
rate. make that 6^2 + 4*(6*4)/2 = 84

Math
well, it sounds like the triangles have two sides of length 5, and an altitude of 4. That means, each triangle consists of adjoining 3-4-5 right triangles, making a base of 6, which is also the side of the square. So, the area of the pyramid is 4^2 + 4*(6*4)/2 = 64

Math
A net is an unfolding of a line drawing of the pyramid. Each line represents an edge of the original figure. So, they will give a way to determine the dimensions and thus the area and volume of the pyramid. If you google "square pyramid net" you will see lots of ...

Math
well, what do the lines on the net represent? The surface area is the area of the square base, plus 4 isosceles triangles.

Trigonometry
see your previous post, in related questions below. Also, recall that tanA = sinA/cosA

#1,#2 use any online grapher, such as wolframalpha.com #3 well, what do you have to add to 4 to get to -4? (4,-4) + (-8,?) = (-4,7) #4. Put the words into algebra: T: (x,y) -> (x-4,y+1) ... #5 no figure available #6 to reflect in the x-axis, change the signs of the y-...

physics help
Knowing the radius of the circle is not enough. Is it a full semi-circle, or a smaller section? A speed bump 1cm high will not do much.

calculus
if the NS sides have length x and the EW sides have length y, then if he spends the entire \$500, 2*4x + 2*8y = 500 or, 2x+4y=125 A = xy = x(125-2x)/4 This is just a parabola, with its vertex (maximum area) at (125/4, 15625/32) For #b, y=1878/x, so the cost c is 8x+16y = 8x+16(...

Trigonometry
cosA = -3/5 so A is ins QIII sinA = -4/5 now the rest is easy...

math help? burnet help.
1/(4x) takes 1/4 as long to get to the same y, so the graph is compressed by a factor of 4 horizontally. the rest is easy ...

Algebra 1
how is 3^5^2 a radical? Looks like exponents to me. 3^5^2 = 3^(5^2) = 3^25 no idea where a enters the picture ...

Algebra 1
If x sold early, and y sold on the day, then x+y <= 800 6x+9y >= 5000

Physics
review your text. I'm sure it says that 1/R = 1/15 + 1/10

math
There are 10 fruits. P(banana) = 1/10 since there is only one banana. After the 1st pick, there are only 9 fruits left. Now it should be clear what P(pear) is. P(both) = P(banana) * P(pear)

Math
let u = 3^x. Then you have u - 1/u - 1 = 0 u^2-u-1 = 0 solve for u, and then x = log3u

Math
measuring from the tower, if the distance away is x, and the rocket had risen to a height h when first observed, h/x = tan25° (h+4)/x = tan66° Now you can solve for x.

math
note that x^2+25 = (x-5i)(x+5i) The exponents on the factors are the multiplicities.

Precalculus
(x+1)(x-(4-5i))(x-(4+5i)) now just expand that

Math
(a) 500(1/2)^t (b.1) 500(1/2)^(25000/5730) = 500(1/2)^4.363 = 24.3 see what you can do from here.

Precalculus
y = (x-4)(x-7i)(x+7i) now just expand that.

math 1
rubbish. If you followed the steps, what were they?

math 1
so, what were your calculations? If we are to analyze why your answer may be wrong, show us how you got it.

AP physics (multiple choice)
v is changing direction, and a is also changing direction. so, what do you think?

Just Curious
take a look at some of the questions and the responses. You decide.

Precalculus
Assuming you mean real coefficients, then D

Precalculus
complex zeroes occurs in pairs, so ...

math
X/Y = A/B X/Y + 1 = A/B + 1 (X+Y)/Y = (A+B)/B (X+Y)/(A+B) = Y/B

Math
area scales as the square of the ratio. So, the square of the ratio is (125/20) = 25/4. So, the ratio is 5/2 Volume scales as the cube of the ratio, or 125/8

math
yes no - positive powers only. the leading term is usually the highest power. The constant term is just a number, with no variables.

math
in terms of Friday time, Sat at 2:26:33:07 = 26:26:33:07 So, just subtract 26:26:33:07 -7:44:35:16 to allow for borrowing, that's the same as 25:85:92:107 -7:44:35:16 --------------- 18:41:57:91

Algebra
note that each term has an x. So, factor it out: x(x+6)

math
2x^2-2x 2x^2-15

math
try adding: 2/7 + 1/3 = 13/21 so, 13/21 - 1/3 = 2/7

maths
1/4 = 16r^6 r = 1/2 16,8,4,2,1,1/2,1/4

Geometry
they are similar

math
a = 4?r^2 da/dt = 8?r dr/dt v = 4/3 ?r^3 = ar/3 dv/dt = 1/3 (r da/dt + a dr/dt) Now just plug in your numbers

MATHS
ever heard of math notation? (sin^4x-cos^4x)/(1-sin^2x) = (sin^2x+cos^2x)(sin^2x-cos^2x)/cos^2x = tan^2x-1

Maths
google is faster. For any pyramid, v = 1/3 Bh where B is the area of the base.

Maths
v = 1/3 Bh, so 100 = 1/3 B * 12 Now solve for B, the area of the square base, and then the side is easy

calculus
assuming you want to integrate, let u=ln(3+x) dv = x dx du = 1/(3+x) dx v = x^2/2 ?u dv = uv - ?v du ?x ln(3+x) dx = x^2/2 ln(3+x) - 1/2 ?x^2/(3+x) dx Now just divide, and you will have easy stuff left.

calculus
let u = (lnx)^2 dv = x^-3 dx du = 2lnx/x dx v = -1/2 x^-2 ?u dv = uv - ?v du ?(lnx)^2/x^3 dx = -(lnx)^2/(2x^2) - ?(-lnx)/(x^3) dx Now repeat with u=lnx and you will be left with just a power of x to integrate.

Precalculus
since complex roots occur in conjugate pairs, (x-3)^2 (x-(5+i)) (x-(5-i))

Precalculus
y = (x-2)^2 (x+4)^3 now just expand that.

Fraction
48

Math
Let's make things easy by ending up with 21L of the 1:20 solution. That will contain 1L of pure solution. (2/7)x + 0(21-x) = (1/21)(21) x=7/2 So, mix 3.5L of the 2:5 mixture with 17.5L of water

physics homework
depends on the spring constant. asking twice won't help ...

Algebra
1200 * e^(.05*6) = 1619.83 too bad you didn't include your work ...

Math
2^2(7+2^2)+0*1 71-(20+7) There are lots of ways

Mathematics
If (x-1) is supposed to be the altitude, then (x+6 + 3x-4)/2 * (x-1) = 119 x = 8

Maths
Huh? LCM(140,n) has to be at least 140...

Maths
you are correct. I misread the problem. Can you see where?

Maths
(2x+2x+2x)-(10+19+29)+x = 90 Hmmm. I suspect a typo.

Chemistry
see related questions below

Science
(30m/s)/(60s) = 0.5 m/s^2

physics
The resistance of the parallel component is 30R/(R+30) If R' is the equivalent resistance of the circuit, R' = 1/(1/30 + 1/R) + 6 = 36(R+5)/(R+30) The current through the 6? resistor is 120/R' = (10R+300)/(3R+15) The voltage drop across R is [30R/(R+30)]/[36(R+5)/(...

Math
T13/T6 = ar^12/ar^5 = r^7 (3/16)/24 = 1/128 = (1/2)^7 so, ...

maths
506 base 6 does not exist, since base 6 numbers consist only of the digits 0-5.

Math
use the law of sines to show that the base is divided into equal lengths. Then that will imply that the angles at the base of the altitude are also equal, so they are both 90 degrees.

math
50 * (1788/3725)

algebra
just solve the equation x^2 + (1/2 x + 11)^2 = (2x+1)^2 x = 8

college algebra
C(x) is just a parabola. Its minimum value is at the vertex, where x = -b/2a = 7

math
90 years is 3 half-lives. That means that 1/8 of the original amount remains. So, the 1 mg that has decayed represents 7/8 of the original amount. So, starting out at 8/7 g, 1/7 g = 14.27mg remains. ---------------------------------- after 4 half-lives, 1/16 of the original ...

college algebra
Sorry, that -3072 means its initial height (at t=0) is 3072 feet below ground.

Math
since |y| > y, y < 0, so |y| = -y x>|y|, so x+y>0 ==> |x+y| = x+y |x+y|-|x|+|y| = x+y-x-y = 0

Math
4^x = 6 2^x = ?4^x = ?6 8^x = (2*4)^x = 2^x * 4^x = 6?6 or, 8^x = (4^(3/2))^x = (4^x)^(3/2) = 6^(3/2) = 6?6

Math
(A+B)/2 = A + B/10 A/2 + B/2 = A + B/10 A/2 = 2/5 B A = 4/5 B A.B = 4.5

Calculus
2?r^2 + 2?rh = 20 so, h = 10/?r - r the volume is v = ?r^2h = ?r^2(10/?r - r) = 10r-?r^3 so, find r when dv/dr=0

Math
If the walk has width w, then since the parkland occupies 80% of the area, (30-2w)(5-2w) = 0.80*30*5 w = 0.4396m

Calculus
h+4s = 14 v = hs^2 = (14-4s)s^2 so find s when dv/ds = 0

Physics
since V is constant, and PV=kT, P/T = k/V is constant. So, you want P such that P/(273+25) = 7/(273+15)

math
because 1/c = c^(-1)

Math
check your prior post in the related questions below ...

consider f'(1) where f(x) = ?x where you should have written the limit as (?(1+h) - ?1)/h

Pre calculus
p(x) = (x-11i)(x+11i) = x^2 - (11i)^2 = x^2+121

Physics
distance = speed * time so, time = distance/speed

22.50 * 1.15 = 25.875

well, how did you figure it out?

Math
well, the base has area 132/11 = 12 so ...

Calculus
(a) c = 13(4x+y+4x+y) + 5(3y) = 112x+41y (c) xy=9, so y=9/x, and c(x) = 112x + 369/x now find x where dc/dx = 0

Math
huh? Just solve (75+x)(225-5x) = 16000 x = 5 so, ...

Precalculus
a) ok b) The average cost is the cost per unit, or c?(x) = c(x)/x So, c?(x) = 0.02x + 0.5 + 40/x The marginal average cost is thus c?'(x) = 0.02 - 40/x^2

Algebra - rats
I see other typos. The final answer is correct, but let me just do it right: Since the vertex and focus both lie on the line x = -2, the axis of symmetry is vertical, meaning the equation is (x-h)^2 = 4p(y-k) Since the focus above the vertex, p is positive. You know that the ...

Algebra - typo
As you noticed, the axis is vertical, on he line x = -2

Algebra
Since the vertex and focus both lie on the line x = =2, the axis of symmetry is horizontal, meaning the equation is (x-h)^2 = 4p(y-k) Since the focus above the vertex, p is positive. You know that the parabola x^2 = 4py has the vertex at a distance p from the focus. Here, that...

Math, Algebra
If you drop an altitude to the center of the base, then looking from the side you have a right triangle with legs 4 and 22. So, the hypotenuse of the triangle (the slant height of the pyramid, and the altitude of each triangular face) is h = ?(4^2+22^2) = ?500 = 10?5 That ...

MAth help connexus
c - review the section on functions, esp. the vertical line test.

math - trigonometry
one walks on a heading, not a bearing. a) Note that angle Q is 90 degrees, so you have a right triangle. Easy... b) This is the correct use of "bearing." If the bearing is x, then tan(x+25) = 18.7/11.4 A diagram will show you why.

Math Measurment unit test
1. A = bh 2. A = bh/2, so looks good.

math
2/s = 1/4 + 1/5

math
well, the volume of water flowing in every second is 1.2cm * 350cm/s = 420 cm^3/s Now divide the volume of the tank by the inflow rate to get the time (in seconds)

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