Wednesday
April 1, 2015

Posts by Steve


Total # Posts: 30,251

Calculus
when a is a constant, g'(au) = a g' You know that if y=2x, y'=2(1) y=3x^7, y' = 3(7x^6) The constant is just a multiplier, and carries through. So, what you have is g = √2 u + √7√u
February 26, 2015

math
you need more than just the scale.
February 26, 2015

Math
the time in the air is t when h=0 again. So, just solve for h(t) = 0. the max height is the vertex of the parabola, clearly when t=4.
February 26, 2015

math
y = x/3 + 7 now just plug in x=18 and evaluate for y.
February 26, 2015

Math
You found the union, not the intersection. 3.3: You found A-B, not the union. 4.4: Again, you found the union. The intersection is the elements in all three sets: {1,5}
February 26, 2015

math
one recall that the roots are -b/2a ±√(discriminant) so, if the discriminant is zero, both roots are -b/2a
February 26, 2015

math
the lateral surface area is just the circumference times the height. So, a = 4*15 = 60 if you have to include the ends, then that is additional 2πr^2, where r = 4/2π
February 26, 2015

MATH
graphing the other methods are exact.
February 26, 2015

Math
(2/5)(1/5) + (3/5)(1/3)
February 26, 2015

math
there are several similar problems in the related questions below.
February 26, 2015

Math!! Help ASAP
11.4 is correct.
February 26, 2015

maths
3 5/9 = 32/9 40 1/2 = 81/2 So, the common ratio, r^6 = (32/9)/(81/2) = 64/729 r = 2/3 T5 = 32/9 * (2/3)^4
February 26, 2015

maths
ar = a+4 ar^2 = ar+9 Now just solve for a and r
February 26, 2015

calculus
no ideas on any of the questions? They gave you the function, so things should just fall right out.
February 26, 2015

math
y = (x^4+4)^2 (x^3+4)^4 ln y = 2ln(x^4+4) + 4ln(x^3+4) 1/y y' = 8x^3/(x^4+4) + 12x^2/(x^3+4) y' = [8x^3/(x^4+4) + 12x^2/(x^3+4)]*[(x^4+4)^2 (x^3+4)^4] Now you can massage that as you will. Eventually you can arrive at y' = 4x^2 (x^3+4)^3 (x^4+4) (5x^2+8x+12)
February 26, 2015

Math
By "side" I assume you mean one of the bases. If the other base is x, then we have (6+x)/2 * 13 = 91 (6+x)/2 = 7 6+x = 14 x = 8
February 26, 2015

programming
as usual, the average is the sum of all the ages, divided by the number of pupils. Count the pupils as they come in: num_pupils = sum_of_ages = 0 loop { read in years, months num_pupils++ age_in_months = years*12 + months sum_of_ages += age_in_months } average_age = ...
February 26, 2015

math
see related questions below
February 26, 2015

maths
the values are 1/√3, 1, √3, ... I think you can see what the constant ratio is.
February 26, 2015

arithmetic
the sides of such a hexagon are the same as the radius of the circle.
February 26, 2015

Math
since 3x^2+11x-20 = (3x-4)(x+5) you have log(3x-4)+log(x+5)-log(3x-4) = log(x+5) log3(27) = 3 log(18) = log(9) + log(2) So, you have 1/6 (3) + 2 + log3(2) - log3(2) = 5/2 625 = 5^4, so you have log5(5^(4/3)) = 4/3 surely you meant loga w. If so, you have log_a(x^6 y^3 z^4 w^3)
February 26, 2015

Calculus
That's what I get. For shells, ∫[2e^-6,2] 2π(4-y)(6+log(y/2)) dy comes out the same. Amazing!
February 26, 2015

Calculus
2e^-x has a y-intercept of 2, so you have a sort of triangular region with vertices at (0,2),(6,2),(6,2e^-6) using washers, each washer has an area π(R^2-r^2) where r = 4-2 = 2 and R = 4-y = 4-2e^-x Now the integral is just π∫[0,6] (4-2e^-x)^2-2^2) dx You can ...
February 26, 2015

Math Help!
each face of the pyramid is an isosceles triangle with base 8 and height √(22^2+4^2) To see this, view the pyramid from the side. Drop an altitude to the center of the base, and you have a right triangle whose hypotenuse is the height of the triangular face.
February 26, 2015

math
h = p-13 p = 29 so, h = 29-13 = 16 Alan is correct.
February 26, 2015

math
f = 2*5
February 25, 2015

Calc
#1 still does not contain the point (1,1) #2 I don't think there is such an A and B. There is a solution involving sin(√2 x), but that's not gonna fit the requirements. #3 y = e^x - e^2x y' = e^x - 2e^2x = e^x(1-2e^x) so, y'=0 when e^x=0 (never) 1-2e^x = ...
February 25, 2015

Algebra 2
(15^3-7^3)(15^3+7^3) (15-7)(225+105+49)(15+7)(225-105+49) (8)(379)(22)(169) (2^3)(379)(2 11)(13^2) 2^4 11 13^2 379
February 25, 2015

science
draw the batteries on the left, one above the other next over, draw two resistors, in line on the same wire. Connect the ends of the wire to the top and bottom of the batteries. Next over, draw two light bulbs beside each other. Connect the two top ends together, and the two ...
February 25, 2015

math
sure. You can label the axes any way you want. This is often useful when y varies by large amounts.
February 25, 2015

Calculus Chain rule
several ways expand and divide: 6/x * (x^2-1)^4 = 6/x (x^8 - 6x^6 + 4x^4 - 6x^2 + 1) 6(x^7 - 6x^5 + 4x^3 - 6x + 1/x) now take derivative: 6(7x^6 - 30x^4 + 12x^2 - 6 - 1/x^2) quotient rule: 6(4)(x^2-1)^3(2x)(x) - 6(x^2-1)^4(1) ----------------------------------- x^2 product ...
February 25, 2015

maths
no way. To plot a point, you have to know the coordinates, or have a way to calculate them.
February 25, 2015

intermeidatealgebra
you sure this isn't a trick question? Look at it carefully.
February 25, 2015

intermeidatealgebra
x+11/15
February 25, 2015

Math
it is C. Sorry, Tracy, not A.
February 25, 2015

Math
two complementary angles add up to 90 degrees. two supplementary angles add up to 180 degrees. So, what do you have to add to 47 to get those values?
February 25, 2015

Geometry
I like E, since you don't provide any clues as to the constraints on x and y.
February 25, 2015

Math Alg. 2
Well, let's see. #1: 1*1 2*1 4*3 8*7 16*17 Hmmm 2^1-1 2^2-2 2^4-4 2^6-8 2^8+16 Hmmm #2: 2 2*2+1 2*5+1 2*11+5 2*26+7 Hmmm 2^2-2 2^3-3 2^4-5 2^5-6 2^6-5 Hmmm. #3: clearly -3,-2,5 repeats as a sequence Sorry. I can't seem to get #1 and #2 right off. They almost follow a ...
February 25, 2015

Math Algebra
f(x0) = 2 f(x1) = f(2) = 2 f(x2) = f(2) must stay 2.
February 25, 2015

Math
look at the units 48 oz = 3 dollars 16 oz = 1 dollar 1 oz = 1/16 dollar so, 6.25 cents/oz you have 16oz/dollar, not 16cents/oz
February 25, 2015

Math- Calc 1
(1,1) is not on that curve. the other questions also have typos.
February 24, 2015

Calculus
d/du(tan u) = sec^2 u so, use that and apply the chain rule: sec^2(sec x) * secx tanx I'm sure you can do #2 y = sec^-1 x sec y = x secy tany y' = 1 y' = 1/(secy tany) y' = 1/(x √(x^2-1)) y = 2^(e^(sinx)) y' = ln2 2^(e^(sinx)) * e^(sinx) * cosx
February 24, 2015

Homework Help (Math)
Write your answer in <x,y> for the following question: If x=<6,-21>, then 1/3x.
February 24, 2015

Pre-Calculus(Trigonometry)
looks good to me
February 24, 2015

math
10x + 25x = 280
February 24, 2015

math
d/c = 2/7 c+15 = 2(d+15) now solve for c and d.
February 24, 2015

Math
6+9r-4(3r-7) 6+9r-12r+28 . . .
February 24, 2015

math
1/8 * 360 = ?
February 24, 2015

honors chemistry
the short answer is that the heavier molecules will require fewer to make up the 10 grams of mass.
February 24, 2015

math
lots of z table stuff here: http://davidmlane.com/hyperstat/z_table.html
February 24, 2015

Motion in 2d
well, y(t) = 39.11t - 4.9t^2 find t when y=0. Then multiply that by Vx. That's how far it went horizontally while going up and back down.
February 24, 2015

algebraic connections
if yu mean 12% per hour, then there will be 100*1.12^10
February 24, 2015

Algebra 2
just plug and chug. 4/(1-r) = 10 2/5 = 1-r r = 3/5 So, now you know the G.P.
February 24, 2015

Math/ Compouded semiannually ?'s
just refer to your compound interest formula. #1: solve for P where P(1+.10/2)^(2*1) = 30000 P = 27210.88 #2: same thing P(1+.12/2)^(2*2) = .25*175000
February 24, 2015

math
convert the two vectors p and w (fir plane and wind) to rectangular coordinates, and add them up. p+w is the resultant velocity on the ground. A vector w in the direction N63W, with magnitude w is <-0.454w,0.891w>.
February 24, 2015

math
Draw a diagram. Let the barge be in the canal, with Kim on the south shore, and Kent on the north shore, both pulling eastward. Then we have Kim: u = <50cos20,-50sin20> u = <46.98,-17.10> Kent: v = <kcos15,ksin15> = <0.966k,0.259k> You want the ...
February 24, 2015

Calculus
I suspect you meant p(x) = 10e^(-.1x) So, the mass will be ∫[0,a] 10e^(-0.1x) dx = -100e^(-.1x) [0,a] = 100 - 100e^(-a/10) = 100(1-e^(-a/10)) If that is 30, then a = 10 ln(10/7) So, the density decreases with increasing distance, meaning more of the mass is closer to x=0...
February 24, 2015

math
using the two-point form for line 1, it is y = 1/6 (x-1) + 1 Now do that for Line 2, and solve the two equations.
February 24, 2015

ALGEBRA
Still wrong.
February 24, 2015

ALGEBRA
#1: nope. That is f(2) -3(-2) = +6 #2 looks ok.
February 24, 2015

math
length is two sides of the rectangle, plus the circumference of the circle. area is the rectangle plus a whole circle.
February 24, 2015

business math
79.44/.8
February 24, 2015

math
so, just count up all of each type, and multiply by their weights.
February 24, 2015

math
13(h+3h) . . .
February 24, 2015

math - oops
make that +10.5
February 24, 2015

math
0.5(x^4 - 3)+12 0.5 x^4 - 1.5 + 12 0.5 x^4 - 10.5
February 24, 2015

Math
because log(0) is undefined, regardless of the base. There is no power of 3 or 5 which equals zero. Take a look at the graph of log x.
February 24, 2015

math
if there is $x at 4%, then the rest (15000-x) is at 5%. Now just add up the interest and solve for x: .04x + .05(15000-x) = 690
February 24, 2015

probability
for both red, we need 2/(n-2) * 1/(n-1) = 1/28 n = 8 Now you can do the other part.
February 24, 2015

math
1.12j = 8400 j = 7500 j/a = 5/3 a = 3/5 j = 4500 (14100-8400)/4500 = 1.267 so, Akinyi's money grew by 26.7%
February 24, 2015

math
2θ = 60,330,420,690,... θ = 30,115,210,345,...
February 24, 2015

math
r = 23.4/1.8 = 13 a = 1/2 * 13^2 * 1.8
February 24, 2015

math
∛(4/3 π) * 4.2 = 6.77
February 24, 2015

Vectors Math
so, have you picked out three vectors?
February 23, 2015

MATH
x y 1 4 5 1 8 6 10 5 not linear, since y changes direction not quadratic, since y changes direction twice. So, guessing cubic, I find -109/1260 x^3 + 1961/1260 x^2 - 2333x + 3130 I doubt that is what you had in mind, but anything else would be even more complicated.
February 23, 2015

Math
age now is x. x = 3(x+3)-3(x-3)
February 23, 2015

pre-cal
sounds like a plan.
February 23, 2015

Physics
the height in meters is h(t) = (Vo sinθ)t - 4.9t^2 Now just find t when h=0. You sure overload the symbol 0.
February 23, 2015

Geometry
where is R?
February 23, 2015

algebra
4/(x+4) + 4/5 = 5/2 4/(x+4) = 5/2 - 4/5 4/(x+4) = 17/10 4 = (17/10)(x+4) 4(10/17) = x+4 40/17 - 68/17 = x -28/17 = x
February 23, 2015

Math
looks like it. Are any of the numbers used more than once?
February 23, 2015

Math
no. 2*0^2 = 0 2*1^2 = 2*1 = 2 2*2^2 = 2*4 = 8 2*3^2 = 2*9 = 18 what you have is (2x)^2, not 2x^2
February 23, 2015

geometry
or, equivalently, if the angle with the ground is greater than the angle with the wall. Because then the side opposite the greater angle is longer.
February 23, 2015

geometry
if the angle the ladder makes with the ground is greater than 45 degrees.
February 23, 2015

Math
There are 9 values, so the median is the 5th value, or 4. No idea when you say that there is no data in 5. If these numbers are like bins containing data, then you have to count the values in each bin, and then find the middle value.
February 23, 2015

Vectors
a+(b•c) is undefined. You cannot add a vector and a scalar.
February 23, 2015

[Calculus] U-substitution for Integrals
u = 3x-5, so du = 3 dx, not just 3 ∫[1,5] (3x-5)^5 dx = 55552 Now, subbing in for u, the limits of integration are not 0-12. Rather, we have 1/3 ∫[-2,10] u^5 du = 55552 Where did you get 165888?
February 23, 2015

Math
count the vehicles: b+s = 21 count the wheels: 2b+4s = 54 assuming scooters have 4 wheels. If they also have 2 wheels, then the problem is bogus.
February 23, 2015

Calculus 2
at height y from the bottom, the area of the surface of the water is (5/4)y*10 ft^2 So, the weight of a thin layer of water at that height is (5/4)y*10*dy *62.4 = 780y dy lbs So, the work to lift all the sheets of water at height y is ∫[1,3] 780y(4-y) dy = 5720 ft-lbs
February 23, 2015

Math
nope C is a right angle obtuse means greater than 90. So, (b) D is a straight angle.
February 23, 2015

Algebra
Take a look here: http://www.wolframalpha.com/input/?i=solve+2x-3y%3C6%2C+4x%2B4y%3C8+
February 23, 2015

Algebra
g(f) = 1/4 f - 3 = (3x+4)/4 - 3 = 3/4 x - 2 f(g(-2)) = f(-7/2) = -13/2 f(g) = 3g+4 = 3(x/4-3)+4 = 3/4 x - 5 f(g)=5 means 3/4 x - 5 = 5 3/4 x = 10 x = 40/3
February 23, 2015

Math
since the new prism has dimensions 1/2 the old one, its volume is 1/8 the old volume.
February 23, 2015

Math
the slope is (-2-5)/(9-5) = -7/4 y-5 = -7/4 (x-5) so, f(x) = -7/4 (x-5) + 5
February 23, 2015

Math
Not quite sure what's what here, but I'll take a stab at it. h(-6) = -1 so, if 3-x = -6: x = 9 j(9) = h(-6)+4 = 3 A' = (9,3)
February 23, 2015

Math
see related questions below
February 23, 2015

algebra
you want to solve for h where π/3 * 25^2 * 7.2 = π * 15^2 * h
February 23, 2015

algebra
just add the exponents and multiply the numbers. What do you get?
February 23, 2015

alleged math
I looked it up in the answer key!!
February 23, 2015

math
∛(250z^4x^7) = ∛(125z^3x^6 * 2zx) = 5zx^2 ∛(2zx)
February 23, 2015

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