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March 23, 2017

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Posts by Steve

Total # Posts: 49,539

Math
just multiply 4x5 by 1/2 and 5/4: 2x2.5 and 5x6.25
February 15, 2017

Calc
f(x) = ?[x,x^8] ln(t) dt The 2nd fundamental theorem is really just the chain rule. f'(x) = ln(x^8)*8x^7 - ln(x)*1/x = 8lnx*8x^7 - ln * 1/x = lnx (84x^7 - 1/x) This works because if g(t) = ?lnt dt g'(t) = ln(t) So, f(x) = g(x^8) - g(x) so, f'(x) = g'(x^8)*8x^7...
February 15, 2017

Math
yes.
February 15, 2017

too-hard probability sir damon/reiny/steve help
I get 5/14 = 0.3571 Damon's answer above is P(b=2)/P(w?0) = 0.3546 Seems they ought to be the same ...
February 15, 2017

Math
1. use the Angle Bisector Theorem. 2. The volume of oil is the area of a circular cap times the length. So, the the formula for the area of a circular cap. Then if the oil volume is v, the depth would have been (v/60?)*15 3. Consider the problem in 2D, and draw a rectangle. If...
February 15, 2017

Math
m(PQS) + x = 180
February 15, 2017

Maths
321
February 15, 2017

maths
a(r^4-1)/(r-1) = 30 a + ar^3 = 18 (r^4-1)/((r-1)(1+r^3)) = 5/3 3r^4-3 = 5r^4-5r^3+5r-5 2r^4-5r^3+5r-2 = 0 (r-1)(r-2)(r+1)(2r-1) = 0 r = 1/2, 1, 2, -1 r=1,-1: extraneous solutions r=2: 2,4,8,16,... r=1/2: 16,8,4,2,...
February 15, 2017

math
ever think of using math notation instead of words? f(x) = 4x for x <= 3 7-x for x > 3 ?[1,7] f(x) dx = ?[1,3] 4x dx + ?[3,7] 7-x dx = 2x^2[1,3] + 7x - x^2/2 [3,7] = [(2*3^2)-(2*1^2)]+[(7*7-7^2/2)-(7*3-3^2/2)] = 16+8 = 24
February 15, 2017

math
3 log(u^2/v) 3(2logu - logv)
February 15, 2017

math 103
the lines intersect at (15,20) The new line has slope -3/5, so it is y-20 = -3/5 (x-15) now massage that into the form you want.
February 15, 2017

Math
not 810, but vh=810*cos42 Read the information that was given to you.
February 14, 2017

math
With 90 cattle, he has 9/4 as many mouths, so 4/9 as long to eat: about 16 days
February 14, 2017

Pre calculus
I cannot find a function of the form 80 + a*e^(-kx) which fits more than two of the points, since when x=0, you have 80+a=176, so a=96 and when x=1 you have 80+96e^-k = 169 e^-k = 89/96 k = ln(96/89) = 0.07571 80+96e^(-0.0757x) does not fit any of the other points.
February 14, 2017

Math
Each inch has 8 1/8-inch parts. So, 3 1/2 inches is 28 times as long. so, ... or, each inch represents 8 feet. so, 3.5 inches is ? feet
February 14, 2017

Math
terms are separated by + and - signs.
February 14, 2017

math
If you plug in your numbers here http://davidmlane.com/hyperstat/z_table.html You will see that it is the 87th %ile.
February 14, 2017

Maths
p+q = 150 3/4 p = 2/5 q I suspect a typo, as the solution is not an integer.
February 14, 2017

Physical Science
thank you
February 14, 2017

Physical Science
A delivery man pushes the button to ring the doorbell. Which of the following forms of energy is not involved in this process? electrical sound mechanical gravitational my answer is gravitational
February 14, 2017

Geometry
You have 4 sides. Add 'em up and subtract from 30 to get the 5th side. Now, how many are equal?
February 14, 2017

Algebra
a) which two factors of 6 add to 5? b) which two factors of 6 differ by 1? c) which two factors of 6 add to 1?
February 14, 2017

Algebra
even integers differ by 2, so the three numbers are x, x+2 and x+4. Now you are told that x(x+2) = 11(x+4)-8 Now solve for x.
February 14, 2017

Math Calc
the range for an angled shot is R = v^2/g sin2? so, plug in your numbers. Remember to convert ft/s to mi/hr.
February 14, 2017

Math - Calculus
Recall that the vertical height h is h(t) = 6 + (810 sin42)t - 16t^2 so, just solve for t when h=0.
February 14, 2017

Algebra
C = P if 0 < P <= 100 Now you can do the part where P > 100, right?
February 14, 2017

Math
No. That is only the numbers between 0 and 15. You are not restricted to positive values.
February 14, 2017

Math
real numbers that are less than 15 means s<15
February 14, 2017

College Algebra
see related questions below...
February 14, 2017

Math 115
In the first 30 minutes you have walked 3 miles. Then, after a total of 40 minutes, you start walking again. So, D(t) = 3 + 1/60 (t-40) if 40 < t <= 65
February 14, 2017

Calculus
Since the fraction is pointless as written, I assume you meant M = (log(E)-11.4)/1.5 1.5M = log(E)-11.4 log(E) = 1.5M+11.4 E = 10^(1.5M+11.4)
February 14, 2017

Exponential Equation
the ^ is used for exponents. I think he means 2e^x^2 + e^x = 4 sometimes they use ^x for ?x In either case, the equation seems unlikely. What do you say, Jason?
February 14, 2017

Exponential
Just use the usual growth formula. It took 388 years, so 24e^(388r) = 4*10^12
February 14, 2017

algebra
correct. It can't get from -2 to 6 without going through 0 somewhere in between. You also need to mention that f(x) is continuous. That is necessary.
February 14, 2017

Alebra 2
recall that x = r cos? y = r sin? now just plug in your numbers.
February 14, 2017

Algebra
?((-12+2)^2+(-19+3)^2)
February 14, 2017

Mathematics
No way. I don't think you mean "permuted." Maybe a bit more explanation of the problem would make it clearer just what you have in mind.
February 14, 2017

maths
7/12 as many stories -- 7/12 as long to type them.
February 14, 2017

Math
You are correct
February 14, 2017

Data
Number the pairs 11 22 33 44 55 66 Now, the left shoes can be arranged in 6! ways. For each of those ways, there are 6! ways to arrange the right shoes. Of those, there are 5! arrangements with one matching pair 4! with two matches, ... 1! with 6 matches. So, it seems to me ...
February 14, 2017

Grade 6: money and measures
1.50n + 10.00*floor(n/30) = 450 n = 246.7 Check: 246 games: 246*1.50 + 10*8 = 449.00 Add $1.50 for the 247th game, and that puts him over the top.
February 14, 2017

algebra
x/15 = cos75
February 14, 2017

math
(1 1/4)^2 = (5/4)^2 = 25/16 ft^2
February 14, 2017

Vectors Q#2
Try reading this discussion. It is the same problem, different points. http://math.stackexchange.com/questions/1300484/distance-between-line-and-a-point
February 14, 2017

Math
13^2
February 14, 2017

Vectors - Maths
since CD = CB, vector CD = v If we let AD be vector z, then u.z = (x-v).(x+v) = x.x-v.v Since |x| = |v|, that is zero. So, u and z are perpendicular.
February 14, 2017

Dependent and Independent variables
a. pick some values for x, and then calculate y. b. pick two of the (x,y) pairs and plot them on graph paper. Draw a line through the two points. All of the other points in your table will also lie on this line. If they do not, you have made a mistake. c. x is independent. You...
February 13, 2017

algebra
w(2w+4) = 48 w(w+2) = 24 4*6 = 24 4*12 = 48 or, you can solve the quadratic.
February 13, 2017

Precalculus
one way: determine where a perpendicular line intersects each, and find the distance between the two points of intersection. another way: determine the equation of one of the lines, then find the distance to it from a point on the other line, suing the formula d = |Ax+By+C|/?(...
February 13, 2017

math
c = 5.00 + 1.50t
February 13, 2017

Algebra
distributive better go back and read up on both topics
February 13, 2017

Geomety
well, 2?r^2+2?rh = 500 2?rh = 320 So, 2?r^2 = 180 ?r^2 = 90
February 13, 2017

Calculus
You need to know the slope of the glider's descent. If he drops straight down, there is no triangle. That is, you need to know his horizontal speed. The vertical drop of 50 ft/s is no good by itself.
February 13, 2017

Math
If the string covers the entire surface area, consider it a bunch of 3-inch circles. Now, you have to know the diameter of the string. If it is 1/20 inch, then there will be 16*20 = 320 loops. So, nail that down, and you can answer the question.
February 13, 2017

calculus
actually, the above solution applies if y is the position function. Since it is itself a rate, you need the average value of the function. That is ?[7,10] x^3+2x^2+3 dx ----------------------------- = 782.25      10-7
February 13, 2017

Math
220+45h Note that when h=0, there is just the flat fee. Then add 45 each time h increases by 1.
February 13, 2017

into to algebra
add up the amount of alcohol in each part. It must equal the alcohol in the final mixture: .15*150 + .70x = .45(150+x)
February 13, 2017

Introduction to negative linear relationships
d = m Maybe you need to specify a bit more.
February 13, 2017

physics
general equation x = a sin(b(t-c))+d Since equilibrium is x=0, d=0 x = a sin(b(t-c)) the period is 9, so b = 2?/9 x = a sin(2?/9 (t-c)) If it travels .4 m in a cycle, the amplitude is 0.1, so x = 0.1 sin(2?/9 (t-c)) Now we have a problem. If x(0) = -0.1, that is its minimum ...
February 13, 2017

Algebra
.20x = 1
February 13, 2017

math
42 lbs
February 13, 2017

099
4x - 30 = -3x - 32 add 3x to both sides 7x - 30 = -32 add 30 to both sides 7x = -2 divide by 7 x = -2/7
February 13, 2017

099 math
1st step: lose the parentheses: 2(2x-7)-16=3(-x-7)-11 4x-14-16 = -3x-21-11 . . .
February 13, 2017

Math
angle C = 85° (180-52-43) Labeling the sides a,b,c opposite angles A,B,C, you want side b, since angle B is the smallest angle. b/sinB = c/sinC b/sin43° = 50/sin85° Now just solve for b
February 13, 2017

science
it takes (50-30)/10 = 2 seconds to reach the final velocity. s = 30t + 1/2 t^2 Now just plug in t=2.
February 13, 2017

Calculus
1. Just use the power rule recall that 1/x^2 = x^-2 2. product and chain rule: y = x^5 (1+x)^5 y' = 5x^4 (1+x)^5 + x^5 * 5(1+x)^4 = 5x^4(1+x)^4 (1+2x) 3. quotient rule. Assuming the usual carelessness with parentheses, y = (4-x^2)/(2x+3) y' = [(-2x)(2x+3) - (4-x^2)(2...
February 13, 2017

Algebra
the slope-intercept rule is called that for a reason... Q2. y=kx, so y/x=k, a constant. You want y such that y/10 = 24/8
February 13, 2017

Algebra
huh?? !! 13/16 = 0.8125 h(13/16) = -16(13/16)^2 + 26(13/16) + 5 = 249/16 = 15.5625 or, h(.8125) = -16*.8125^2 + 26*.8125 + 5 = -10.5625+21.125+5 = 15.5625 Too bad you couldn't be bothered to show your work ...
February 13, 2017

Algebra
don't forget your Algebra I. h(t) is just a quadratic, and the vertex (maximum height) is at t = -b/2a = 26/32 = 13/16 Now use that to find h(13/16)
February 13, 2017

Maths
Sn = n/2 (A1+An) = 8/2 (6+46)
February 13, 2017

Trigonometry
4rpm = 16 in/min, so 1 rev = 4in 2?r = 4, so r = 2/? for the 8" wheel, the ratio of radii is 8/(2/?) = 4? So, if its radius is 4? as big, its speed is 1/(4?) as fast, or 16/(4?) = 4/? in/min It makes 1/(4?) * 4 = 1/? rpm Your unknown radius is ok, but I don't see how ...
February 13, 2017

Calculus for Business Administration and social s
?(432x^12) = ?(8*27*2 x^12) = 6x^4 ?2
February 13, 2017

Maths
Let the length AM=1. Let C be the midpoint of AM. Draw the line CO. It has radius 1/2 + r. Draw the line MO. It has length 1-r. So, in the right triangle CMO, 1/2^2 + (1-r)^2 = (1/2 + r)^2
February 13, 2017

math
you know that the length is between 19.5 and 20.5 meters the width is between 2.5 and 3.5 meters So, use the largest and smallest values to get the range of perimeters.
February 13, 2017

Math 115
45-4.5t
February 13, 2017

Math 115
I'll do one: C(t) = 45 - (45-27)/4 * 4 - (27-18)/2 * (t-6) = 27 - 9/2 (t-6) = 54 - 9/2 t if 6 < t <= 8 This should give a clue to the other parts...
February 13, 2017

math
average value is integral divided by the interval width.
February 13, 2017

math
I'm guessing you meant ?[4,7] (1+x^2) sinx dx or something. Try reposting with better notation. You can also use my notation above at wolframalpha.com to evaluate integrals.
February 13, 2017

math
not quite clear on your notation, but the distance is the integral of the velocity over the interval.
February 13, 2017

Physics
recall that KE = 1/2 mv^2 PE = mgh Now just plug in your numbers.
February 12, 2017

Statistics
visit this site for Z table stuff: http://davidmlane.com/hyperstat/z_table.html
February 12, 2017

Trigonometry
Good work, but I interpret the wheel size as the diameter. If so, same steps apply, just adjusted for the smaller radius.
February 12, 2017

Stats
you can play around with Z table stuff here: http://davidmlane.com/hyperstat/z_table.html For this problem, you find that 99.7% of the area lies less than 2.748 ? above the mean.
February 12, 2017

Algebra
12r+11s = 228 6r+5s = 108 ...
February 12, 2017

Math
I don't know what you mean by it "didn't work." It just shows that the expression is never positive. (x-2)^2 is a square, so it is always positive So, -(x-2)^2 is never positive. Trying to plug a formula into a request for a proof will never work. The logic ...
February 12, 2017

Math
= -(x^2-4x+4) = -(x-2)^2
February 12, 2017

Algebra
x+y = 900 .05x + .08y = 64.50
February 12, 2017

Algebra
12a+2c = 122 7a+8c = 160 ...
February 12, 2017

science
Ca comprises 2/3 of the 1.28g CaCO3, or 0.853g So, assuming that all of the calcium is contained in the CaCO3, the 0.853g is 31.37% of the 2.72g pill
February 12, 2017

college math
The maximum area occurs when the fencing is divided equally among lengths and widths. For all 4 sides fenced, that is a square. In this case, with the length parallel to the wall, we have length=500/2 = 250 and width = 500/2/2 = 125 so the area is 250*125 = 31,250 This is ...
February 12, 2017

math
try typing the equations yourself; copy/paste does not do well here. You can copy and paste the ? symbol as you go.
February 12, 2017

math
.13x + .09(x+700) = 239 x = 800 as above.
February 12, 2017

Geometry
Draw diagonals AC and DF. The hexagon is now divided into a parallelogram (rectangle?) and two congruent triangles. AC and DF can be found using the law of cosines, since all the interior angles are 120 degrees.
February 12, 2017

math
what you mean is 2 <= x <= 5 This is just a parabola, with vertex at (2,-1). So, clearly, f(2) = -1 is the minimum value. The axis of symmetry is at x = 2, so f(5) will be the max on the interval [2,5], since it is away from the axis.
February 12, 2017

Algebra
So, why not use a 1? |3y+4|-1 = 0 |3y+4| = 1 3y+4 = 1 3y = -3 y = -1 3y+4 = -1 3y = -5 y = -5/3
February 12, 2017

algorithm
for i=1 to 5 prompt for marks read marks[i] next i
February 12, 2017

number base help plz
1234 = 4^2 + 2*4 + 3 = 2*8 + 8 + 3 = 338
February 12, 2017

College calculus
x = u/(1 + u^3) y = u^2/(1 + u^3) dy/dx = dy/du / dx/du dy/du = u(2-u^3)/(1+u^3)^2 dx/du = (1-2u^3)/(1+u^3)^2 dy/dx = u(2-u^3)/(1-2u^3)
February 12, 2017

Mathematics of finance 1
see related questions below
February 12, 2017

maths
bricks: 180*6*50 * 8 = ? tank: Assuming a square base, v = 150*150*40/1000 L
February 12, 2017

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