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March 24, 2017

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Posts by Steve

Total # Posts: 49,546

math
Since all of 15,20,30 divide 300, the cube is 20x15x10 blocks in size. So, it can be cut into 3000 blocks. Or, using the idea above, divide the volume of the cube by the volume of a block: 300^3 / (30x20x15) = 27000000/9000 = 3000
March 18, 2017

Algebra
C appears to be a quadratic. As with any quadratic ax^2+bx+c the vertex lies at x = -b/2a So, find C(x) at that value.
March 17, 2017

Algebra
A^-1 exists if |A| is not zero. Here, |A| = 21-20 = 1 so, A has an inverse.
March 17, 2017

English
Which of the following lines from a&p illustrates updikes use of conflict A. the whole store was like a pinball and I didn't know which one they'd come out of. B. you could see the, when Queenie's white shoulders dawned on then, kind of move, or hop, or hiccup but ...
March 17, 2017

algebra
Peter's age now: x Paul's age now: y x-y years ago, Peter was y years old. x = 2(y-(x-y)) x+y = 56 Peter is 32 Paul is 24 8 years ago, Peter was 24 and Paul was 12.
March 17, 2017

Algebra
1/y - 1/(y+5) = 1/10 y = 5 check: 1/5 - 1/10 = 1/10
March 17, 2017

Math
Draw a diagram. You will see that h cot40° = (h+7) cot60°
March 17, 2017

Basic Math
If 13 is the slant height of a triangular face, then the area of the pyramid is just the base plus four triangles: 11*11 + 4*(11*13/2) = 407 I keep having trouble guessing what you mean by "side" especially of a cone.
March 17, 2017

calculus
lim x?? {(5x ? 4)/(5x + 3)}^5x lim x?? {(1 - 7/(5x+3))}^5x Let u=5x lim u?? {(1 - 7/u)}^u I assume you can now see that this is e^-7
March 17, 2017

calculus
using L'Hospital's rule we have lim x?0 (e^x ? e^?x ? 2x)/(x ? sin(x)) lim x?0 (e^x + e^?x ? 2)/(1 ? cosx) still 0/0, so do it again: lim x?0 (e^x - e^?x)/sinx and again: lim x?0 (e^x + e^?x)/cosx ? (1+1)/1 = 2
March 17, 2017

Math - Trigonometry
of course there is. I assume by "opposite" you mean at the same height on the opposite slanting face. If the base has side 2s, and the pyramid has height h, then If the point P is at height y, then it is at a distance x from the central axis of the pyramid. Using ...
March 17, 2017

Linear Algebra
#4 No, ?200 = 14.14
March 17, 2017

Algebra
well, father will be 36 in 4 years, so ...
March 17, 2017

Math - Geometry!!!
Well, it is certainly not a triangle. If you reorder the points a bit, it should be clear:    (3,3),(7,3) (1,1),(5,1)
March 17, 2017

Math
(2/3)(3/4)-(1/6) = 1/3
March 17, 2017

Math
Square ABCD has side length 60. An ellipse E is circumscribed about the square and there is a point P on the ellipse such that PC = PD =50. What is the area of E? I got to the part with the point (30, 30). Now what next?
March 17, 2017

Help Polynomial
Start off with what you know. Substituting x = a,b you have Ra+S = P(a) Rb+S = P(b) Now just solve for R and S.
March 17, 2017

Math, Induction
test for n=1 3.7^2+1 = 14.69 BZZZZTT! But thanks for playing. I suspect a typo in your presentation.
March 17, 2017

Math - Trigonometry
I like 'em. People use decimals because of calculators. When I see °'" I run to my trig tables and do some interpolation!
March 17, 2017

Science
The resistance of each piece is still 25 ohms. Now, if a single 25-ohm wire had been cut into five pieces, then each piece would have had a 5-ohm resistance. That is not what we have here.
March 17, 2017

Science
think about it. The current has 5 different paths it can follow, so the resistance is 1/5 as great. So, 5 ohms 1/R = 1/25 + 1/25 + 1/25 + 1/25 + 1/25 = 5/25 = 1/5 So, R=5 Why would you think it is 1? Time to study some more.
March 17, 2017

Integral Calculus
1st step: go to your DE book and look it up, or go online. Google is your friend. order: highest derivative degree: highest power of highest derivative I can't believe you could not look that up for yourself. www.ul.ie/cemtl/pdf%20files/bm2/DegreeOrder.pdf
March 17, 2017

Geometry proportions in triangles
no diagram, so no way to answer here.
March 17, 2017

algebra
as with any quadratic, the vertex will be at t = -b/2a
March 17, 2017

Maths
180,600.00 (1+.0625)^6
March 17, 2017

calculus
arctan(2x^2y)=x+4xy^2 Using the good old product and chain rules, we get 1/(1+(2x^2y)^2) * (4xy + 2x^2y') = 1 + 4y^2 + 8xyy' Now just collect terms and solve for y': 16x^4y^4 + 4x^4y^2 + 4y^2 - 4xy + 1 - ------------------------------------------- 2x(16x^4y^3 - x...
March 17, 2017

maths
as with any parallelogram, the area A = bh base * height
March 17, 2017

maths
Well, the area of the rhombus is half the product of the diagonals. Draw a diagram and see where that takes you.
March 17, 2017

Last math question of the night plz help quickly!
these are both sloping straight lines. So, they extend forever in all directions. The domain and range are both (-?,?)
March 17, 2017

algebra
9r^2-30r+21 = -4 9r^2-30r+25 = 0 Note that 9 and 25 are perfect squares, so a good thing to try is (3r-5)^2 = 0 Yep, that's it. So, there is a double root of x = 5/3
March 16, 2017

Math
Note that y decreases by 5 when x increases by 1. So, start with y = -5x Now note that y(0) = -1, so you need to adjust the function a bit: y = -5x-1
March 16, 2017

Math
5x = 2x+9 Find x. There are 2x cats.
March 16, 2017

English
COMplex is a noun comPLEX is an adjective Similar to PROtest: noun proTEST: verb (though you'd never guess it if you listen to the news...)
March 16, 2017

English
conjunction
March 16, 2017

Chemistry
4Bi + 3O2 = 2Bi2O3
March 16, 2017

Math
The slant height is 5!! Don't you know a 3-4-5 right triangle?
March 16, 2017

Math
Huh? 3^2+4^2 = 9+16 = 25 = 5^2 get a grip, guy!
March 16, 2017

Math
drop an altitude to the center of the base. Then, looking from the side, you will see that 3^2 + 4^2 = s^2
March 16, 2017

Mathematics
You know nothing about MN, except that it bisects PQ. It could have a long piece on one side of PQ, and be short on the other.
March 16, 2017

Math Algebra
recall that for y = ax^2+bx+c the axis and vertex always lie on the line x = -b/2a
March 16, 2017

Math
If the AP has 1st term=x difference=y a = x+(p-1)y b = x+(q-1)y c = x+(r-1)y Now just plug and chug ... and chug ... and chug
March 16, 2017

Maths
since the speed (km/hr) is constant, 240/2 = 600/x
March 16, 2017

calculus
The asymptote is y=0 So, revolving the area around the x-axis, and using symmetry, v = 2?[0,?] ?y^2 dx = 2?[0,?] ?(1/(x^4+1))^2 dx = 3?^2/(4?2) It looks hard, and it is complicated, but you can start off by noting that x^4+1 = (x^2+1)^2 - 2x^2 and then factor that as the ...
March 16, 2017

Math
x(x-2p)=3(x-p) x^2-2px = 3x-3p x^2-(2p+3) + 3p = 0 for rational roots, the discriminant must be a perfect square. That is, (2p+3)^2-12p = 4p^2+12p+9-12p = 4p^2+9 must be a perfect square. p=2 is one solution check: x(x-4) = 3(x-2) x^2-7x+6 = 0 (x-1)(x-6) = 0 Not only rational...
March 16, 2017

math
18(2+5) = ?
March 16, 2017

math
Lat a = 2^(x-2) b = 5^(y-2) Then you have 4a-25b = 3 a+b = 2 Hmmm. I suspect a typo, since the results are strange.
March 16, 2017

maths
Draw a radius perpendicular to the chord. Draw a radius to the end of the chord. Now you have a right triangle where x^2+6^2 = 8^2
March 16, 2017

Math
so, divide the annual rate by 12 to get the monthly rate.
March 16, 2017

Math
well, how many months in a year?
March 16, 2017

MAth
so, multiply the daily rate by 365 to get the annual rate.
March 16, 2017

MAth
well, how many days in a year?
March 16, 2017

Maths
B is the midpoint of AC. So, its coordinates are the average of the endpoints. So, if C=(x,y) we have (x+4)/2 = 1 (y+5)/2 = -1 Now just solve for x and y.
March 16, 2017

calculus
Just use the product rule y = ?x lnx y' = lnx/(2?x) + 1/?x y" = 1/(2x^(3/2)) + lnx((-1/4)x^(-3/2)) + (-1/2)x^(-3/2) = -lnx/(4x^(3/2))
March 16, 2017

Maths
P = 2(4+6) A = 4*6
March 16, 2017

algebra
Just add up the acid content: .45x + .90(120-x) = .60(120)
March 16, 2017

Series
clearly, 1,3,5 are an AP 2,4,8 are a GP Now just plug in your formulas for partial sums.
March 16, 2017

algebra
0.95x = 4.75
March 16, 2017

@Elsa
I like your 25 stones.
March 16, 2017

Mathematics
I like Elsa's proof, using Heron's formula. Works for me.
March 16, 2017

Mathematics
The line containing (a,0),(0,b) has equation x/a + y/b = 1 This is called the intercept form of a line. Clearly, (1,1) lies on that line if 1/a + 1/b = 1
March 16, 2017

Math, Series
well, just plug and chug 1/(2y) - 1/(y-x) = 1/(y-z) - 1/(2y) (x+y)/(2xy-2y^2) = (y+z)/(2y^2-2yz) (x+y)/(x-y) = (y+z)/(y-z) (x+y)(y-z) = (y+z)(x-y) xy+y^2-xz-yz = xy+xz-y^2-yz y^2-xz = xz-y^2 y^2 = xz y/x = z/y Thus x,y,z form a geometric progression
March 15, 2017

Math, Series
Do you mean 1/(y-x), 1/(2y), and 1/(y-z) or 1/(y-x), (1/2)y, and (1/y)-z ??
March 15, 2017

Math
Again, the curve is unbounded. If you mean y=(x^3/3)+x^2+x+1/(4x)+4 then here is the graph: http://www.wolframalpha.com/input/?i=(x%5E3%2F3)%2Bx%5E2%2Bx%2B1%2F(4x)%2B4 So, which part of the curve do you want?
March 15, 2017

Calculus
Consider the interior of the bowl as a stack of thin circles. At height h, the circle has area ?r^2 = ?(16(h+1)) So integrate that from 0 to 2
March 15, 2017

Math
If there are no correct answers, then the possible scores are 0,2,4,...,24 If 1, then 5,7,9,...,27 If 2, then 10,12,14,...,30 I think you can see the pattern here. Just make a 12x12 table and fill in the scores. Then cross them off a list of values from 1-60. Those remaining ...
March 15, 2017

math
If she travels x minutes at 70m/min, then the distance is 70x meters. It takes her 2 minutes longer at 60m/min. 70x = 60(x+2) x = 12 So, the distance is 840 meters. Her normal speed takes her 22 minutes, so she leaves at 7:38
March 15, 2017

maths
http://formulas.tutorvista.com/math/orthocenter-formula.html This will give you the orthocenter, if you have the vertices of a triangle. If you set up your right triangle with the right angle at C=(0,0) then let the other two vertices be at A=(a,0) and B=(0,b). Then the right-...
March 15, 2017

math
I think that the ? is just a way of giving us the slope of the ladder. If the firefighter has climbed a distance z to a height h, then we have x^2+y^2 = 29^2 w^2+(y-h)^2 = (29-z)^2 when ?=?/3, x = 29/2 and y=29?3/2 w = (29-z)/2 and h = z?3/2 when z=6, then, w = 23/2 and h=3?3 ...
March 15, 2017

math
they are the same. 10/10, 5000/5000, ...
March 15, 2017

Math
any plane intersection with a sphere is a circle.
March 15, 2017

Algebra
What were you expecting it to "add up" to? -4b * (1-b)/b = -4b(1-b)/b = -4(1-b) = 4b-4
March 15, 2017

algebra, series
The n'th term is ar^(n-1) Sn = a(1-r^n)/(1-r) = 1/4 4a(1-r^n) = 1-r 4a - 4ar^n = 1-r 4a - 4ar^(n-1)*r = 1-r ar^(n-1) = (1-r-4a)/(4r) I can't see how you can solve for r and a. There are many possible solutions. n=1: a=1/4 n=2: a(1+r) = 1/4 a = 1, r = -3/4 a = -1/3, r...
March 15, 2017

Pre-Algebra
12 is 3/7, so 4 is 1/7 Now how much would you pay?
March 15, 2017

sir damon steve damon damon help maths
That is correct. The average value of a function over an interval if ?[a,b] f(t) dt ------------------ b-a
March 15, 2017

Algebra
You know the factors will be (3n-?)(n+?) or (3n+?)(n-?) where the ?? pairs are 1,4 or 2,2 So, just poke around a bit and you will soon find that (3n-4)(n+1) works
March 15, 2017

Math
12/28 as much time, so 28/12 as many workers. 28/12 * 3 = 7
March 15, 2017

Math
distance = speed * time Since their distances are the same, if Jim's speed is x, then x(1/4) = (12)(1/3) x = 16 mi/hr Or, you can consider it like this. Jim takes 3/4 as long, so his speed must be 4/3 as great. 4/3 * 12 = 16
March 15, 2017

english
8 - 10 paragraphs on The Odyssey part 1. PLEASE, I WONT TAKE THIS FOR GRANTED. god bless. i tried but i cant read it very well
March 15, 2017

Math
The curve is unbounded. Also, there appears to be a typo. Why the +x+14x? As with any curve, its length over a given interval [a,b] is s = ?[a,b] ?(1+y'^2) dx
March 15, 2017

Math1
(a) do not know the formula (b) your text formatting sucks. try writing fractions as 3/4 and sequence terms as t7 or t20
March 15, 2017

Math! Help Hurry!
each small block has a volume of (1/4)^3 so the whole lot has a volume of 576 * (1/4)^3 = 9 ft^3
March 15, 2017

Math! Help Hurry!
I thought you said these problems were all different. They look exactly the same to me. Figure the volume of one of the small blocks, and use that to divide into the whole volume. 3 1/4 = 13/4 so the box has a volume of 13/4 * 3 * 1 = 39/4 ft^3 each small block has a volume of...
March 15, 2017

Math and Hurry Please!
2304 * (1/4)^3 = 36 cm^3
March 15, 2017

Math
the new mix of 32+8=40 oz contains 4+8=12 oz of cream 12/40 = 30%
March 15, 2017

Caclulus
#1 I assume that x,y,z are integers, or there is no maximum sum. The minimum sum would be 3?500 ? 23.811 500 = 2^2 5^3 so its factors are 1,2,250 1,4,125 1,5,100 1,10,50 1,20,25 2,2,125 2,5,50 2,10,25 5,5,20 5,10,10 5,25,4 Now pick the largest and smallest sums. #2 v = ?r^2h...
March 15, 2017

Mathematics
Take a look at the distances for each stone, numbering them outward. I'm assuming that we only include the distances actually carrying stones. The actual distance walked would be twice that. # d 1 10 2 20 3 30 ... n 10n So, after collecting n stones on each side, the ...
March 15, 2017

Mathematics
In that case, you must have forgotten your Algebra I. Look at what you know: a+7d = 2(a+2d) 8/2 (2a+7d) = 39 or, massaged a bit, a = 3d 8a+28d = 39
March 15, 2017

intermediate algebra
-2x - 5 < -2 -5 < 2x-2 -3 < 2x -3/2 < x or, x > -3/2 do the others similarly.
March 15, 2017

intermediate algebra
add 3 to each part
March 15, 2017

mat222
your copy/paste skills are severely lacking. What's so hard about this? You have the function pieces and their domains. Just plug in your numbers for the proper part.
March 15, 2017

Algebra
since ?WED ? ?FRI, ?R ? ?E So, solve for x.
March 15, 2017

Mathematics
consider the top of a large cone which has been cut off to leave the frustrum. Draw a side view. Using similar triangles, we know that the top of the bucket is 3/4 as high as the uncut cone. So, the piece that was cut off has an altitude of 15 cm. Subtract the small top of the...
March 15, 2017

maths
This should help a lot. You can construct the vectors u and v for the two orthocenters, and then just get the magnitude of |u-v| http://mathforum.org/library/drmath/view/70440.html
March 15, 2017

maths sir damon reiny or steve help!steve see
surely you know about the chain rule. ?u/?r = ?u/?x ?x/?r + ?u/?y ?y/?r = 2x sin(t) + 2*0 = 2x sin(t) similarly for ?u/?t
March 15, 2017

calculus
f = (6-x)e^-x f' = (x-7)e^-x f" = (8-x)e^-x f"=0 at x=8 f(8) = -2e^-8 so (x,y) = (8,-0.00067) See http://www.wolframalpha.com/input/?i=(6-x)e%5E-x+for+6+%3C%3D+x+%3C%3D+11
March 15, 2017

calculus
(a) [?[0,?] (10 sin(x)-5sin(2x)) dx]/(?-0) = 20/? (b) 10sin(c)-5sin(2c) = 20/? c ? 1.238 or 2.808
March 15, 2017

calculus
well, the weight is 44-0.2t now integrate that over the required distance.
March 15, 2017

maths
AC = AB+BC = a+b and so on. Of course they sum to zero, since that is a closed path.
March 15, 2017

Trig
so, think back to your Algebra II days and finish it up. What you have is correct, but make it look good: x^2-4x + y^2+4y = 0 x^2-4x+4 + y^2+4y+4 = 8 (x-2)^2 + (y+2)^2 = 8 http://www.wolframalpha.com/input/?i=r%3D4cos%CE%B8+-+4sin%CE%B8
March 15, 2017

math
unchanged
March 14, 2017

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