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Posts by Steve

Total # Posts: 50,479

maths
If there are e erasers, p pencils, and q pens, we have 2e+4p = 240 6e+p+2q = 395 e+p+4q = 415 If A is the matrix of coefficients, then A^-1 = 1/84 (-2 16 -8) (22 -8 4) (-5 -2 22) Then you have (e p q) = (30 45 85) See here: http://www.wolframalpha.com/input/?i=inverse+%7B%7B2,...

Science
No ideas? Surely you have a calculator.

Algebra2
thank you

Algebra2
4x^2+4y^2=64. what are the domain and range? my answer is domain;all real numbers range;-4<=4<=4

Math c2
well, 3?(x^2+1) = ?(9x^2+9) = ?(3x)^2 + 9) So, it looks like a horizontal compression by a factor of 3.

Math
well, for usage over 50 therms, the bill for x therms is y = 67.65 + 1.1917(x-50) So, plug in your y values and solve for the x values.

maths
well, where is x^2-x-6 = 0? You cannot divide by zero, and the square root is not real for negative values, so ... the domain is x values where x^2-x-6 is positive.

algebra
Think about it like this. With 5 types of seeds, there are 5 choices for the 1st flower. For the 2nd flower, there are only 4 choices. For the 3rd flower there are 3 choices. Now you know how many ways the 3 flowers can be planted. But if all you want is the combinations, the ...

math
4x^2+19x-5 = (4x-1)(x+5) The roots (places where the graph crosses the x-axis) are -5 and 1/4 So, where do you think the value is negative?

Precaculus
(0.1 cm^3)/(4?/3 * (5*10^-3 cm)^3) = 0.1/(5.24*10^-7) = 190986 cells V(t) = 0.1 * 2^(t/20)

maths
you know the circumference of a circle is ?d, right? Think of the circle as a round piece of string. Cut it and lay it out straight. That's how far the wheel travels in one complete turn.

Math
sum means add (product means multiply) same mistake. "/" means divide -8n ok your answers are ok if you meant x+(-3) times means multiply. You really seem to have a problem here... and yet you got y-5 correct.

Math
2(80+x) = 410 area = 80x

Math
well, he spent 1/4 + 1/3 + 1/5 = 47/60

English
clearly, neither. It just mentions shoes of no specific kind.

Math
5P2 * 12P4 = ?

Algebra 2
or, for a more condensed presentation, type in your coefficients here and see all the details. http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

Math
they must be flying in the same vertical plane, if they are traveling with an angle relative to the horizontal ... Also, I suspect A's speed is 100?3 m/s, not mi/s. Using the law of cosines, 500^2 + (100?3 t)^2 - 2(500)(100?3 t)(?3/2) = (100?3 t)^2 They will crash in 5/3 ...

science
well, how many moles of Fe2O3 in 108kg? Now balance the equation: Fe2O3 + 3CO -> 2Fe + 3CO2 Now you can see how much CO is used.

Math
well, 27+28 = 55

calculus
the 3-foot radius and 2-foot depth means that y = 2/9 x^2 The arc length of the parabola is ?[0,3] ?(1+y'^2) dx Now just rotate that, remembering that the circumference of a circle is 2?r.

Math
well, what about zero factors?

math
2(w + w+9) = 110

ATI TEAS 6 practice
as for the -20x+20, 5(x-2)^2 = 5(x^2-4x+4) = 5x^2-20x+20

ATI TEAS 6 practice
not much factoring here. 5(x-2)^2 = 125 (x-2)^2 = 25 x-2 = ±5 x-2 = +5: x = 7 x-2 = -5: x = -3

Math age problem/ Solving Multi step Equations
a = 2m-15 a+m = 12 ...

Calculus Answer Check
good numbers, but what about [0,10]?

Math
*sigh* 7 5/16 + 3 3/4 = 7 5/16 + 3 12/16 = 7+3 + 5/16+12/16 = 10 17/16 = 11 1/16 clearly you need to review operations with fractions.

Math
7 5/16 + 3 3/4 place fractions over a common denominator and add.

math
42

Hot math questions
not if S is the number of shoes in S/2 pairs ...

Maths trigonometry
trés simple -- x = Sin Alfa / (335sin59) now just get out your calculator. sure looks like a Law of Sines problem to me.

FUR. MATHS
judging from the student's alleged name, we want something like (f?g)(x) = f(g) = 2g-1 = 2(5-2x)-1 = ...

Algebra math 150
I guess it depends on what you are trying to do...

maths
The range of f^-1(x) is (-9/4,?) x = (1-5y)/(2y) 2xy = 1-5y y = 1/(2x+5) so, f(x) = 1/(2x+5) domain is (-9/4,?)

Math
?[1,5] (ln2x - lnx) dx = ?[1,5] ln2+lnx-lnx dx = ?[1,5] ln2 dx = 4ln2

Geometry
Hard to say what you did wrong, since you didn't show your work. First, learn to use parentheses: 9/(4x-2) = 12/(3x+2) 9(3x+2) = 12(4x-2) 27x+18 = 48x-24 21x = 42 x = 2

Long Division
SEE ALL THE DETAILS HERE: http://calc101.com/webMathematica/long-divide.jsp

math
if you say so. Hard to tell, since you don't say when you leave...

calculus
Each shell has thickness dy and height x = 2/y So, the volume v is v = ?[2,4] 2?rh = ?[2,4] 2?y(2/y) dy = ?[2,4] 4? dy = 8? As a check, you can use discs, getting v = ?(4^2-2^2)(1/2) + ?[1/2,1] ?(R^2-r^2) dx where R=y and r=2 v = 6? + ?[1/2,1] ?((2/x)^2-2^2) dx v = 6?+2? = 8?

math question
so, move left-right 1 and up-down 2 or left-right 2 and up-down 1. One such point will be (1+1,2+2) = (2,4) I think you will find 8 such points, not 4.

maths
I can't figure out what circle (O, OP ) is passing from A means.

maths
I assume that "circle (P,12)" means a circle with center at P and radius 12. If so, then the distance between the circles is 25-12-5 = 8 Draw the diagram. Label O the point midway between the circles. Then we have two right triangles PAO and QBO PO=16 and PA=12 QO=9 ...

Geometry
surely you know that the circumference of the semi-circle is 300? so, add that to the 3 straight sides,

Precalculus
6

math NEED HELP ASAP
.60x + 1.00(120-x) = .70*120

Calculus
either 5+2/x < 1 or -(5+2/x) < 1 In the first case, x is in (-1/2,0) In the 2nd case, x>0 or x < -1/3 . . .

Math
so, just solve for d when -0.02d^2+2.6d-66.5 = 0

Math
#1 y = (3/4)x+b 7 = (3/4)*4+b b=4 so, y = (3/4)x+4 Clearly (0,0) does not satisfy that equation #2 x/y can be zero if x=0 Only y cannot be zero. #3 ok #4 volume is always in cubic units. Area is square units. #5 85+92+80+90+x = 5*89 x = 98 How could you possibly believe such a...

math
do the () first 10-7=3 3 squared=9 4 times 9 =36 36 times 7 =252 252+4=256

math
subtract the 25 from 14

math
15+19=34 34-6=28 28/2=14 14-25=negative 11

Algebra2
thank you very much

Algebra2
find a quadratic function in standard form for each set of points. (-1,2),(0,1),(1,-4)

mathemadics
come on. Take a stick and break it into thirds. How many pieces are there?

math
at 3 m/s, time t: 3t time t+1: 3(t+1) = 3t+3

Math
coconut: (3/5)(1/3) = 1/5 angel: (2/5)(1/6) = 1/15 assuming no cakes are coconut ... If all the cakes are either coconut or angel food, then coconut: (3/5)(1/3) + (2/5)(5/6) = 8/15

Algebra
how about 7*2*9 ?

Algebra
2 legs per animal yields 26 legs There are 6 extra legs, so what does that say? Think about what happens when you replace a chicken with a sheep.

Calculus
Too bad you didn't show your work... f' = 1 + 2cosx f'=0 when cosx = -1/2 x = 2?/3, 4?/3 f" = -2sinx f"(2?/3) < 0, so that is a maximum f"(4?/3) > 0, so that is a minimum See the graph at http://www.wolframalpha.com/input/?i=x%2B2sinx,+for+x+%...

Math
m = kh now plug in your numbers

Math
a:b = 3:8 b:c = 1:6 = 8:48 a:b:c = 3:8:48 a:c = 3:48 = 1:16

Math
no idea what the shaded region is.

Algebra
plot each line and the solution is where they intersect.

math 73
add up the amount of fat in the milk and cream. It must equal the amount in the mix. If there are x gallons of cream, then the rest (20-x) is milk. So, .22x + .02(20-x) = .04(20)

Geometry
2(w+78) = 260

maths curve need help
First step: draw the graphs! They intersect at (0,0) and (1,1). You want to rotate a small lens-shaped area. To find the volume, you can do two methods. Think of the volume as a stack of discs with holes (washers). The holes are there because a slice of area is rotated around ...

Math
#1 #2 are ok the volumes are in the cube of the linear ratio. So, v' = (10/15)^3 v = 8/27 v = 160 This is due to the fact that each dimension scales the same way. In the case of the sphere, replace r by (2/3)r in the formula. Then you get v = 4?/3 r^3 v' = 4?/3 (2/3 r...

Algebra2
a = a1 = 2*1-3 = -1 d = an+1-an = (2(n+1)-3)-(2n-3)) = 2 Now just use your sum formula S10 = 10/2 (2a+9d)

Algebra2
What is the sum of the first 10 terms of the sequence defined by an = 2n - 3?

Math
good start, but 16 years means 32 payments.

physics
recall that the index n is defined by n = c/v

Calculus
I assume a triangular cross-section. So, the width of the water surface when it has a depth of y is y/2. Thus the volume of water of depth y is v = (1/2)(y)(y/2)(8) = 2y^2 dv/dt = 4y dy/dt Now just plug in your numbers

math
same as for any regular n-gon: area = 1/2 perimeter * apothem But it will be very close the the circle.

Trig
well, (u-3)(u+1)/(u+1) = u-3 as long as u ? -1

Algebra
yes

Algebra
don't you recognize 8^2 and 9^2 ?

Maths
2(5x+3x) = 128 x = 8 so, ...

Algebra
well, 32 = 2^5 that should help

Calculus
e^(ax) = e^(a/b * bx) = (e^(a/b))^(bx) C = e^(a/b)

Geometry
42

Calculus
If I read all those words correctly, you mean ?[-3,3] f(x) dx where f(x) = f1: ?(4-?(x+1)) for -3 <= x <= 1 f2: |x-2|-1 for 1<x<3 Unfortunately, for x < -1 the first piece is complex, not real. Anyway, fix the presumed typo and just plug in the pieces ?[-3,1] f1...

math
Draw the figure. If the height is h, then you have a 40-by-h rectangle in the center, with extra lengths of x and 25-x on the longer base. x^2+h^2 = 56^2 (25-x)^2+h^2 = 39^2 x^2-56^2 = (25-x)^2 - 39^2 x = 224/5 so, h^2 = 56^2-x^2 = 28224/25 h = 168/5 so, the area is (40+65)/2...

Math/Calculus
Consider the set of nested shells of thickness dy. v = ?[0,4] 2?rh dy where r=y and h=218-x = (y+2)^3+2 v = ?[0,4] 2?y(218-((y+2)^3+2)) dy = 8192?/5 as a check, using discs of thickness dx, v = ?[10,218] ?r^2 dx where r=y=(x-2)^(1/3)-2 v = ?[10,218] ?((x-2)^(1/3)-2)^2 dx = ...

Calculus
assuming you mean 1<=x<=5, we have, using discs, v = ?[1,5] ?(R^2-r^2) dx where R=x^(1/5) and r=(x/5)^2

Calculus
each triangle at a distance x from (0,0) has a base of 2y = 2?(64-x^2) So, the total volume, taking advantage of symmetry is v = 2?[0,8] bh/2 dx = 2?[0,8] 2?(64-x^2)*2?(64-x^2)/2 dx = 4?[0,8] (64-x^2) dx = 4096/3

Calculus
Find the volume of the solid whose base is the circle x^2+y^2=64 and the cross sections perpendicular to the x-axis are triangles whose height and base are equal. Find the area of the vertical cross section A at the level x=7.

calculus
h^2 = 6^2 + x^2 h dh/dt = x dx/dt when h=10, x=8, so just plug in the numbers 10 dh/dt = 8*2 dh/dt = 8/5 m/s

math
The only way I can make sense of what you wrote is to interpret it as p = mq^3 q = nr^2 p = m(nr^2)^3 = mn^3 r^6 = kr^k p varies directly as the 6th power of r.

Calculus AP Exam review explanation pls
#1. Recall that the average value is 1/? ?[-?,0] 3^cos(x) dx use your calculator to find that the integral is 4.16348 Divide that by ? and you get 1.32528 #2 is just another integral. Just as distance is ? v(t) dt, here the total change in momentum is ? cost dt since ? p = F ?...

Algebra 2
correct

math
35/60 of the circumference of a complete circle of radius 6 cm.

math
The distance between pencil centers on each side is 1 diameter, or 7mm. At each corner there is a quarter-circle, so the entire length is 4*7 + ?*7 = 7(4+?) mm

math
Draw the diagram, with two congruent triangles at the ends. Notice that the two right triangles are 6-8-10.

science
that means that 90% remains, so (1/2)^(t/1590) = 9/10 t = 241.7 years

maths
h/4 = tan45°

math
(2(3x+100)+100)/4 - x/2 = ?

math
x/y = a/b (x+y)/y = x/y + 1 = a/b + 1 = (a+b)/b the rest follows

math
let's say that for each ounce of 5-cent rice, you buy k ounces of 6-cent rice. 7(1+k) = (5+6k)(6/5) k = 5

calculus
h' = 3/20 ?x the length of cable is s = 2?[0,20] ?(1+h'^2) dx = 2?[0,20] ?(1+9x/400) dx = 44.2 ft Now figure the weight.

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