Wednesday
April 1, 2015

Posts by Steve


Total # Posts: 30,251

calculus
u = arcsec(x) x = sec(u) dx = secu tanu du the integrand now becomes u secu tanu du Now use integration by parts and it's a cinch. If still stuck, just google it and I'm sure you can find lots of detailed solutions.
February 12, 2015

computer science
ok. It's pretty cool, believe me. Oh, yeah -- can't post it here.
February 12, 2015

math
since the plane is aimed basically SW, but its velocity is basically SE, I'd call it a tail wind, since its southward direction is increased. That's quite a side wind, though, as well. Does the vertical speed matter when considering this?
February 12, 2015

Trigonometry
the plane flies on a heading, not a bearing. the distance east is 200*sin(90-137) = 200cos(47) = 136.4 km
February 12, 2015

math
If the expensive side has length x, and the other is y, then the cost is 75x+30*2y = 1750 The area is a = xy Since y = (1750-75x)/60 = (350-15x)/12 a = x(350-15x)/12 = 1/12 (350x-15x^2) This is just a parabola with vertex at x = 35/3. That is x, so now you can figure y.
February 12, 2015

Geometry
sorry. I get a message saying I have to log in to view the page. Better describe the diagram.
February 12, 2015

Geometric progression
r = 1/2 try that to get started.
February 12, 2015

statitics
all probabilities must be positive.
February 12, 2015

math
Just add up all the powers of 7: 7^[(-1/5)-(-7/5)+(3/5)] = 7^((-1+7+3)/5) = 7^(9/5) The line in question is wrong. 1/7^(-7/5) is NOT 7^(5/7) it is 7^(7/5) 7^(-1/5) is NOT 7^5 it 1/7^(1/5) Reciprocals just cause the exponent to be minus what it was, not the reciprocal. Better ...
February 11, 2015

algebra
the two candles have height h and h+1 The shorter candle burns at the rate of h/4 in/hr The longer burns at the rate of (h+1)/6 in/hr So, h-(h/4)(2.5) = (h+1) - (h+1)/6 * 4 h = 8
February 11, 2015

physi<u>c</u>s
aaa
February 11, 2015

algebra
sorry - 2/3 of 135 = 90, as expected. single is 105/285 = 36.8%
February 11, 2015

algebra
the population has m men and w women. Assuming that each married person has a single spouse, 2/3 m = 3/5 w So, m = 9/10 w So, assume there are 9 men and 10 women. The given fractions don't give integer results, so we need to multiply the proposed population. LCM(3,5) = 15...
February 11, 2015

geometry
recall that the length of the altitude is the geometric mean of the two segments of the hypotenuse. That is, w+9 = √(8*18) = 12
February 11, 2015

Algebra 1
A box shaped like a rectangle prism has a height of 17 inches and a volume of 2,720 in^2. The length is 4 inches greater than twice the width. What is the width of the box?
February 11, 2015

Algebra 1
Find the solution of x^2+14x+112=0 I don't think that there is a solution
February 11, 2015

Algebra 1
What is a solution of x^2 +6x=-5? my answer is -1
February 11, 2015

Algebra 1
What is the value of n so that the expression x^2+11x+n is a perfect square trinomial?
February 11, 2015

Algebra 1
thank you
February 11, 2015

Algebra 1
The area of a rectangle is 30 ft^2. The length is 1 less then 3 times the width. How wide is is the rectangle?
February 11, 2015

Algebra 1
my answer is 42 feet
February 11, 2015

Algebra 1
A ball is thrown into the air with the in initial upward velocity of 60 ft/s. It's height (h) in feet after t seconds is given by the function h=- -16t^2+60t+6. What will the height be at t=3 seconds?
February 11, 2015

Algebra 1
my answer is 3 seconds
February 11, 2015

Algebra 1
A ball is thrown into the air with the in initial upward velocity of 45 ft/s. It's height (h) in feet after t seconds is given by the function h=- -16t^2+45t+6. After about how many seconds will the ball hit the ground?
February 11, 2015

Algebra
the acceleration is (41m/s)/(.28s) = 146.43 m/s^2 F = ma
February 11, 2015

math
for the horizontal asymptote, as x gets large, only the highest powers matter. So, what is x^2/9x^2 ? For vertical asymptotes, they can only occur where the denominator is zero. 9x^2-44x-5 = (9x+1)(x-5) so, when is that zero?
February 11, 2015

Icp
F = ma
February 11, 2015

math
Seems like you'd have to know the various amounts of debt and interest, doncha think?
February 11, 2015

math
see the 1st related question below
February 11, 2015

Geometry
42° = 1/2 (large-small) so, large-small=84° but, large = 7/3 * small 7/3 * small = small+84 4/3 * small = 84 small = 63 large = 147 So, since the three arcs add up to 360°, 63+147+x = 360 x = 150° A nice discussion of the topic is found at http://www....
February 11, 2015

Maths
Hmmm. Looks like 20 to me, too. There aren't any fractional laps to worry about.
February 11, 2015

Geometry
Suppose the sides were exactly 3,10,12. The perimeter would be 25. But, the actual perimeter is 400 = 16*25 So, the sides are 16*3,16*10,16*12 = 48,160,192
February 11, 2015

math
blue beads are 3,6,9,12,15,18 green ones are 7,14 so, what do you think?
February 11, 2015

math
a = pi r^2 = 38.5 r^2 = 38.5/pi r = 3.50 c = 2pi r = 22.06 Now, for the square: s = 22.06/4 = 5.515 a = 30.42
February 10, 2015

math
(.05*540 + .80*(720-540))/720 = 23.75%
February 10, 2015

9th Grade Math
(4πx^2)/(3x^2) = 4π/3 = 4.19
February 10, 2015

math
2(q^2-3q) = 2q^2-6q So, you want to add up 2q^2-6q+q+10+q^2 Keep like powers together, and you end up with (2+1)q^2 + (=6+1)q + 10 3q^2-5q+10
February 10, 2015

Math
7/15 - 6/15 = ?
February 10, 2015

Math
you are correct
February 10, 2015

geometry
90+62+x = 180
February 10, 2015

vectors
Looks good to me.
February 10, 2015

Math
x^6 z^-1/3 / -125 y^-9 z^8/3 = x^6y^9/-125z^3 (x^6y^9/-125z^3)^-1/3 = -5z/x^2y^3
February 10, 2015

messy systems
n+q = 50 5n+25q = 1030 Now just solve for n and q.
February 10, 2015

Math
20% of 20 quarts is 4 qt. Adding 5 qt of red will make 9/25 = 36% red
February 10, 2015

math
If the boys average n points each, then just add up the total points g = 3b 18g + nb = 17(g+b) 54b + nb = 17(3b+b) 54b + nb = 68b 54+n = 68 n = 14
February 10, 2015

Algebra 1
thank you
February 10, 2015

Algebra 1
A carpenter is putting a skylight on a roof. If the roof measures 10x +89 by 7x+7 and the skylight measures x+5 by 3x+3, what is the area of the remaining roof after the skylight is built?
February 10, 2015

Algebra 2
a good long division site is http://calc101.com/webMathematica/long-divide.jsp
February 10, 2015

Algebra 2
wolframalpha.com is a good graphing site. Just type in your function or equation.
February 10, 2015

calculus
<mumble>
February 10, 2015

Algebra 1
A sports team is building a new stadium on a rectangular lot of land. If the lot measures 6x by 10 x and the sports field will be 1x by 4x, how much land will be left over>? My answer is 56x^2
February 10, 2015

Algebra 1
A garden will be on a rectangle lot 5x by 10x. The garden will be circular with a radius of 3x. How much land will be left over after the garden is built?
February 10, 2015

math
surely you know how many lb/kg and in/cm. If not, look them up to do the conversions.
February 10, 2015

Math
because the order or arrangement matters. Otherwise, it'd just be a combination.
February 10, 2015

math
s = t^3-3t^2-8t+c use s(1) = 10 to find c, then evaluate s(2)
February 10, 2015

Math
because ((x+10)*4+200)/4-x = 60 for any x
February 10, 2015

Math - eh?
no idea. You need to provide a little more context. Also a little better grammar.
February 10, 2015

math
you want arcsin(4/5) in QI and QII, where sine is positive.
February 10, 2015

Math
The only one I get is 1+2+3-4+5+6+7*8-9 = 60
February 10, 2015

Math
If there are x at 40 cents, and y at 16 cents, then you know that x = 2y 40x+16y=576
February 10, 2015

Math
k = 9/2 s s = k-28 Now just solve for k and s and figure k+s
February 10, 2015

algebra
the slope is (1/2 - 2/5)/(-4/5 - 1/3) = -3/34 So, now you can use the point-slope form to get the equation for the line as y = -3/34 (x - 1/3) + 2/5 You can massage that into the form you want. I assume you can get rid of the fractions.
February 10, 2015

maths please help and explain
Using somewhat more conventional notation, we have 4((1/2)x+2) = 2((2/3)x-3) 2x+8 = (4/3)x-6 (2/3)x = -14 x = -21 (3x-6)/(2y) = 4 3x-6 = 8y 3x-8y = 6 (2y+3)/4 = 2x 2y+3 = 8x 8x-2y = 3 Doing a little scaling, that's the same as 3x-8y = 6 32x-8y = 12 Now subtract and you ...
February 10, 2015

math
Clearly, the nth branch produced 2^(n-1) oranges.
February 10, 2015

Trigonometry
if the height matters, then you need to give some indication of the angles of elevation. Just knowing the direction tells us nothing about the buildings' locations. The N8°W and N10°E are angles measured on the ground. Apparently the 10m is a straight line on the ...
February 10, 2015

Math
the bedroom is 12*12 = 144 ft^2 the living room is 12*18 = 216 ft^2 so, the bedroom's area is 144/(144+216) of the total. The price of the carpet is irrelevant.
February 10, 2015

math
5/6 < 1 (5/6)^2 is (5/6)(5/6) < 5/6 so, what do you think?
February 10, 2015

Math
h(t) = 8t - 2.5t^2 so, just find the vertex of that parabola.
February 10, 2015

Math
clearly, x=3 and y=2
February 10, 2015

Math
I get 2x = y+2 2z = x+1 so, t=7
February 10, 2015

math
42°
February 10, 2015

Geometry
well, surely you must recognize that ∠TUS ≅ ∠SUT, so that means that 4x+16 = 2(18x-8) 4x+16 = 36x-16 x = 1 So, ∠SUT = 20° ∠RUS = 10° No idea what ∠RUT is, since you haven't said anything about the relative locations of the points...
February 10, 2015

Pre-Calculus
oops. wrong vertex. Should be (0,628.0925) y = -0.007015x^2+628.0925
February 10, 2015

Pre-Calculus
you can do all the graphing stuff. Lots of online places for that. Given the definition of cosh(x), you have the arch as c(x)=693.8597-68.7672(e^0.0100333x+e^-0.0100333x)/2. The vertex of the arch is at c(0) = 693.8597-65.7672 = 828.0925 the arch meets the ground where c(x) = ...
February 10, 2015

math
If the amounts invested are x,y,z then we have x+y+z = 5000 x+y = z .02x + .03y + .04z = 145 Hmmm. I get -500 for y. Sure there's no typo in the problem?
February 10, 2015

Calculus
a = ∫[-1,1] y dx
February 9, 2015

Math
I see six dimensions. That's some room!
February 9, 2015

math
no idea what you mean when you say you have some numbers "on a prism."
February 9, 2015

Vectprs and Scalars
if a and b are vectors, a•b is a scalar. a×b is a vector. the dot product • is only defined for two vectors. The cross product × is only defined for two vectors. So, 1,3,5,11 are scalars 6,8,9,10 are vectors 2,4,7,12 are undefined
February 9, 2015

math
180° is completely straight.
February 9, 2015

Algebra 2
I have an idea. Why don't you show your work? To start, square both sides, then collect terms and square again. √(2x+1) + √(2x+6) = 5 (2x+1) + 2√(4x^2+14x+12) + (2x+6) = 25 √(4x^2+14x+12) = 9-2x . . .
February 9, 2015

Algebra 2
x^4-x = 0 x(x^3-1) = 0 x(x-1)(x^2+x+1) = 0 do the other the same way. Factor it out. Each of the factors may be zero.
February 9, 2015

Algebra 2
enter your function or equation at wolframalpha.com
February 9, 2015

physics
the range of the ball is R = (v^2 sin2θ)/g so just find v such that (v^2 sin(102°))/9.8 = 14
February 9, 2015

Vb
well, Integer is misspelled.
February 9, 2015

Math
1x4 = 4x1 commutative property of multiplication?
February 9, 2015

math
X and Y are 80° apart. Each time zone is 15° wide. So, the towns are 5 1/3 time zones apart. Depending on their proximity to the zone lines, they could be 6 or 7 hours apart. The rest I'm sure you can do with normal trig operations. If not, show how far you got, so...
February 9, 2015

Math
7/8 - 5/6 = 21/24 - 20/24 = 1/24
February 9, 2015

Math
The sum from 1 to n where n is even (2k) is (2^2-1^2) + ... + ((2k)^2-(2k-1)^2) = (2+1)(2-1) + (4+3)(4-3) + ... + (2k+2k-1)(2k-2k+1) = 3+7+...+4k-1 = k/2 (3+4k-1) = k(2k+1)
February 9, 2015

maths
we want F such that Fx = 3ye^(3x) - 2x Fy = e^(3x) Clearly F = ye^(3x)-x^2
February 9, 2015

algebra
d = 1.22√(50+5)
February 9, 2015

mathematics
d/1200 = cot 28°
February 9, 2015

trig - eh?
Hard to tell, but I am assuming that you meant to say that the taller building is 6/5 as far away as the shorter building. If so, then the shorter building is 5/6 as far away, or 20/3 m. Something tells me the heights matter, but I can't see how, from the data. The ...
February 9, 2015

trig
Draw a diagram. You will see that the distance d is given using the law of cosines: d^2 = 415^2 + 120^2 - 2*415*120*cos 100°10'
February 9, 2015

maths
since you have only provided a single value for each coordinate, and the planes are all perpendicular to an axis, the intersection must clearly be (-2,8,5).
February 9, 2015

maths
there are lots of matrix calculators online. wolframalpha shows that the calculation is http://www.wolframalpha.com/input/?i=solve+{{12%2C4%2C17%2C11}%2C{14%2C8%2C9%2C4}%2C{3%2C7%2C2%2C5}%2C{5%2C12%2C9%2C7}}*{{p}%2C{q}%2C{r}%2C{s}}+%3D+{{5}%2C{8}%2C{12}%2C{7}}
February 9, 2015

math
1,33 10,42 100,132 5003,5035 I think you need a bit more information.
February 9, 2015

Math
d/p = 3/4 p-3 = d p = 4d/3, so 4d/3 - 3 = d d/3 = 3 d = 9
February 9, 2015

Math
f:j = 3:4 j:s = 7:6 LCM(4,7) = 28, so f:j = 21:28 j:s = 28:24 f:j:s = 21:28:24 so, f:s = 21:24 = 7:8 total candy = 54 pieces. You want a box with only 9 pieces. Each box has 18 pieces now. So, just move 9 from one box to another.
February 9, 2015

math
cos(x) = √3/2 if x = 30° or 330° So, 3θ+120 = 30, 330, 390, 690, ... θ = -30, 70, 90, 190, ... So, pick the values in your domain.
February 9, 2015

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