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scott8148 answered: 6619 problems
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Polynomials-and-rational-expressions/611194: Please help me factor 5z^2-23z-10
1 solutions

Answer 384877 by scott8148(6628) About Me  on 2012-05-15 13:20:39 (Show Source):
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factors of -10 that can "combine" with factors of 5 to produce -23

5 * (-5) = -25 ___ 1 * 2 = 2

(5z + 2)(z - 5)


Linear_Equations_And_Systems_Word_Problems/611192: having trouble setting this up. The volume of a 5in tall cone varies as the square of the radius the volume is 14.1in^3 when the radius is 1.5in. find the volume when the radius is 3in.
1 solutions

Answer 384874 by scott8148(6628) About Me  on 2012-05-15 13:16:10 (Show Source):
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"The volume of a 5in tall cone varies as the square of the radius"
___ the radius is multiplied by 2, so the volume is multiplied by 2^2


Trigonometry-basics/611125: How do I solve the right triangle with these as given?
C = 90degrees, c = 12, and A = 26degrees40minutes
IThis is sorta a duplicate since the first question I forgot to add C = 90degrees. I'm sorry. Please someone answer this question. Thank you.
1 solutions

Answer 384826 by scott8148(6628) About Me  on 2012-05-15 08:46:57 (Show Source):
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a = c * sin(A)

b = c * cos(A)

B = C - A


Permutations/611073: There are 5 students sitting around a table. How many different pairs of students could be formed from those students? I think it is 10
1 solutions

Answer 384818 by scott8148(6628) About Me  on 2012-05-15 08:33:42 (Show Source):
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you are correct

each of the 5 students can pair up with the other 4 ___ 5 * 4 = 20

BUT ... Pam paired with Tom is the same as Tom paired with Pam, so ___ 20 / 2 = 10


Reduction-of-unit-multipliers/610953: My daughter had this problem in her homework last night. My husband and I both believe the correct answer should be 1; however, the teacher counted it wrong and said the correct answer was 36 in/yd. I still believe that would be 1 if it were totally simplified, but I could very well be wrong. Please help settle my mind on this one:
3ft/1yd x 12in/1ft
Thank you!
1 solutions

Answer 384684 by scott8148(6628) About Me  on 2012-05-14 19:34:51 (Show Source):
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this is an exercise in units conversion, the units "cancel" just like a variable

%283+ft+%2F+1+yd%29+%2A+%2812+in+%2F+ft%29 = 36+in+%2F+yd

given that there are 3 feet in a yard and 12 inches in a foot, how many inches in a yard?


if you believe the answer should be one, I would be curious as to the technique and (especially) the units...

with further thought ___ you got one because 36 in IS a yd, so the numerator and denominator cancel
___ this serves as a check on the conversion


what was the actual homework question?


Rectangles/610862: A square has dimensions of x feet by x feet. A rectangle is 4 feet longer than the length of the square. Find the area of the rectangle
help please
1 solutions

Answer 384633 by scott8148(6628) About Me  on 2012-05-14 16:38:51 (Show Source):
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the area of the square is ___ x * x or x^2

the rectangle is 4 ft longer, so its area is ___ x * (x + 4) or x^2 + 4x


Polynomials-and-rational-expressions/610860: 11w(squared)-14w+3
factor.
please show me how to work this promblem out!(: thanks
1 solutions

Answer 384628 by scott8148(6628) About Me  on 2012-05-14 16:17:24 (Show Source):
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(11w - 3)(w - 1)


Age_Word_Problems/610820: Ten years from now, A will be twice as old as B. Five years ago, A was three times as old as B. What are the present ages of A and B?
1 solutions

Answer 384609 by scott8148(6628) About Me  on 2012-05-14 14:26:52 (Show Source):
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"Ten years from now, A will be twice as old as B" ___ A + 10 = 2(B + 10)

"Five years ago, A was three times as old as B" ___ A - 5 = 3(B - 5)

subtract the equations (to eliminate A); solve for B; then substitute back to find A


Polynomials-and-rational-expressions/610813: How is this factored completely?
36x-100y^2 x
1 solutions

Answer 384603 by scott8148(6628) About Me  on 2012-05-14 13:53:22 (Show Source):
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common factors ___ 4x (9 - 25y^2)

difference of squares ___ 4x (3 + 5y) (3 - 5y)


Travel_Word_Problems/610762: A boat can travel 55 miles up the river in the same amount of time it takes to travel 65 miles down the same river. If the speed going down the river is 7 MPH faster than the speed goin gup the river, what is the speed of the boat going up the river?
1 solutions

Answer 384573 by scott8148(6628) About Me  on 2012-05-14 12:42:09 (Show Source):
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t = d / r ___ the times are equal

55 / x = 65 / (x + 7)

"cross" multiplying ___ 55x + (7 * 55) = 65x


Travel_Word_Problems/610761: If Steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes, and Jack can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to mix the 20 drinks?
I keep doing 20/5+20/10+20/15=1/x
and cant seem to get there - what's wrong w/ my formula??
Thanks a million for your help :)
Trish
1 solutions

Answer 384570 by scott8148(6628) About Me  on 2012-05-14 12:33:59 (Show Source):
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your equation calculates the time for the three of them to make one drink (1/x), try using 20/x


Quadratic_Equations/610753: Can someone help me solve this problem? Thank you so much!
Solve x² + 4x – 7 = 0 by completing the square. How many solutions are there?

1 solutions

Answer 384566 by scott8148(6628) About Me  on 2012-05-14 12:26:25 (Show Source):
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x^2 + 4x = 7

x^2 + 4x + (4/2)^2 = 7 + (4/2)^2

(x + 2)^2 = 11

x + 2 = ± √11

x = -2 ± √11


Average/610747: Your test grades are 87, 75, 85 and 95. What is the lowest grade you can get on the next test and still maintain at least and 85 average?
1 solutions

Answer 384565 by scott8148(6628) About Me  on 2012-05-14 12:22:01 (Show Source):
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87 + 75 + 85 + 95 + x = 5 * 85


Length-and-distance/610729: The diameter of a circle has end points (1,2) and (3,2). Where is the center of the circle?
1 solutions

Answer 384543 by scott8148(6628) About Me  on 2012-05-14 09:03:51 (Show Source):
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midway between the endpoints


Polynomials-and-rational-expressions/610726: If 27^n=9^8,then n=?
1 solutions

Answer 384541 by scott8148(6628) About Me  on 2012-05-14 08:41:32 (Show Source):
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(3^3)^n = (3^2)^8

3^(3n) = 3^16


Quadratic_Equations/610715: use factoring to find the zeros of y=x2-7x-8 and the axis of symmetry
1 solutions

Answer 384540 by scott8148(6628) About Me  on 2012-05-14 08:34:37 (Show Source):
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0 = (x - 8)(x + 1)

the axis of symmetry lies midway between the zeros
___ in this case ___ x = 7/2


Travel_Word_Problems/610710: Lusine is on a boat going to an island twelve miles away for a picnic. The way there, with the current, it takes her 3 hours while the way back, against the current, it takes her 4 hours. What is the speed of her boat and what is the speed of the current?
1 solutions

Answer 384539 by scott8148(6628) About Me  on 2012-05-14 08:30:40 (Show Source):
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b + c = 12 / 3

b - c = 12 / 4

add the equations to find b (c will be eliminated); then substitute back to find c


Travel_Word_Problems/610706: Shantanu believes he has the makings of a country music star, so he is flying from Baltimore to Nashville, 700 miles away, to try out his luck. The ride there with the wind takes four hours. A few months later almost broke he heads back, on the same plane and the same wind. The flight then, against the wind, takes five hours. What is the speed of the plane and what is the speed of the wind?
1 solutions

Answer 384538 by scott8148(6628) About Me  on 2012-05-14 08:27:50 (Show Source):
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p + w = 700 / 4

p - w = 700 / 5

add the equations to find p (w will be eliminated); then substitute back to find w


Travel_Word_Problems/610690: flying with the wind, a pilot flew 600 miles between two cities in 4 hours. the return trip against the wind took 5 hours. find the rate of the plane in calm air and the rate of the wind.
1 solutions

Answer 384537 by scott8148(6628) About Me  on 2012-05-14 08:21:33 (Show Source):
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p + w = 600 / 4

p - w = 600 / 5

add the equations to find p (w will be eliminated); then substitute back to find w


Radicals/610687: What is the 4th root of 81x^8y^16?
Could you please send work as well?
thanks
1 solutions

Answer 384536 by scott8148(6628) About Me  on 2012-05-14 08:18:40 (Show Source):
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(3^4 * x^8 * y^16)^(1/4)

3 x^2 y^4


Rate-of-work-word-problems/610599: A pool can be filled in 45 hours and drained in 60 hours. How long will it take to fill the pool if both the fill and drain pipes are on? Enter your answer to the nearest hour. (Enter only the numerical value)

1 solutions

Answer 384478 by scott8148(6628) About Me  on 2012-05-13 20:36:40 (Show Source):
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in 45hr, enough water has been put in to fill the pool; but 3/4 of it (45/60) has drained out

so if it takes 45 hr to fill 1/4; how long to fill the whole pool?


Distributive-associative-commutative-properties/610558: factor by grouping 2r^2-11r-6
1 solutions

Answer 384477 by scott8148(6628) About Me  on 2012-05-13 20:11:23 (Show Source):
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(2r^2 - 12r) + (r - 6)

2r(r - 6) + 1(r - 6)

(2r + 1)(r - 6)


Geometry_Word_Problems/610557: What is the length of the radius of a circle with the center at O(-3,4) and passes through the point P(2,-5)?
1 solutions

Answer 384476 by scott8148(6628) About Me  on 2012-05-13 20:09:02 (Show Source):
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use the distance formula between the two points


Quadratic_Equations/610554: I could use some help on this problem.
Which of these is the first step in solving x^2 + 6x + 1 = 0 by completing the square?
a. (x + 6)^2 = -1
b. x^2 + 6x = -1
c. x^2 + 6x + 9 - 9 + 1 = 0
d. (x + 6)^2 + 1 = 1
I came up with A., but I'm not sure if that is correct.

1 solutions

Answer 384464 by scott8148(6628) About Me  on 2012-05-13 18:24:42 (Show Source):
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it's b

the next steps are:

x^2 + 6x + (6/2)^2 = -1 + (6/2)^2

(x + 3)^2 = 8

x + 3 = ± 2√2

x = -3 ± 2√2


Trigonometry-basics/610543: How do you prove that 1-cos2x=2sin^2x? I don't even know how to start this problem. Please help =)
1 solutions

Answer 384458 by scott8148(6628) About Me  on 2012-05-13 18:06:28 (Show Source):
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cos(2x) = cos^2(x) - sin^2(x)

1 - [cos^2(x) - sin^2(x)] = 2 sin^2(x)

1 - cos^2(x) + sin^2(x) = 2 sin^2(x)

1 - cos^2(x) = sin^2(x)

1 = sin^2(x) + cos^2(x)


Equations/610516: 4*x+x^2=5
1 solutions

Answer 384447 by scott8148(6628) About Me  on 2012-05-13 17:07:30 (Show Source):
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x^2 + 4x - 5 = 0

factoring ___ (x + 5)(x - 1) = 0


Quadratic-relations-and-conic-sections/610515: determine whether the following equations describe a parabola , a hyperbola and ellipse a circle ?
a) x^2-4x+y^2-12y=60
b) 2x^2-4x+y^2-12y=60
c) x^2-4x-2y^2-12=60
d) -4x+y^2-12y=60
e) 2x^2-4x+2y^2-12y=-60
1 solutions

Answer 384445 by scott8148(6628) About Me  on 2012-05-13 17:05:43 (Show Source):
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a) x and y both squared and positive with equal coefficients -- circle

b) x and y both squared and positive with unequal coefficients -- ellipse

c) x and y both squared, one negative and one positive -- hyperbola

d) only y is squared -- parabola with a horizontal axis, opening to the right

e) x and y both squared and positive with equal coefficients -- circle




Linear-systems/610513: Christine went shopping and bought each of her 9 nephews a gift, either a video costing 14.95. Or a cd costing 16.88. She spent 148.06 on the gifts. How many videos and how many cd's did she buy?
1 solutions

Answer 384444 by scott8148(6628) About Me  on 2012-05-13 16:56:46 (Show Source):
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c + v = 9

(14.95)v + (16.88)c = 148.06

solve the system using substitution or elimination


Miscellaneous_Word_Problems/610500: Bob's Burger Barn sold 495 hamburgers today. The number sold with cheese was 6 less than twice the number sold without cheese. How many hamburgers with cheese were sold and how many without cheese were sold?
This is what I came up with so far : (2w - 6) + c = 495, but still couldn't find the answer.
1 solutions

Answer 384443 by scott8148(6628) About Me  on 2012-05-13 16:53:37 (Show Source):
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two unknowns usually means two equations

"sold 495 hamburgers today" ___ c + w = 495

"The number sold with cheese was 6 less than twice the number sold without cheese" ___ c = 2w - 6

substituting ___ (2w - 6) + w = 495

solve for w, then substitute back to find c


Pythagorean-theorem/610477: 5^2 + 12^2 = 13^2
25 + 144 = 169
169 = 169 I understand the mathwork involved in Pathagorean Triples and Theorems, but I am having trouble with my assignment. The assignment says to find a method or formula outside of my textbook and generate five pathagorean triples. I need to confirm validity of these pythagorean triples using the pythagorean theorem formula: a2 + b2 = c2, but Please remember that a2 + b2 = c2 is NOT the formula you're looking for to generate the triples with, it is only to verify each of the
triples (at least 5). I am confused plz help me.
1 solutions

Answer 384440 by scott8148(6628) About Me  on 2012-05-13 16:39:59 (Show Source):
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a^2 + b^2 - 2b^2 = a^2 - b^2 = (a + b)(a - b)

a^2 + b^2 - 2b^2 = c^2 - 2b^2

(a + b)(a - b) = c^2 - 2b^2 ___ (a + b)(a - b) + 2b^2 = c^2

the sum times the difference, plus twice the smaller squared; equals a perfect square


this will work, but I'm sure there must be other methods


Linear_Equations_And_Systems_Word_Problems/610457: soybean meal is 18% protein; cornmeal is 9%. How many pounds of each should be mixed together in order to get 360-lb mixture that is 14% protein?
1 solutions

Answer 384435 by scott8148(6628) About Me  on 2012-05-13 15:52:40 (Show Source):
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(18%)s + (9%)c = (14%)360

s + c = 360