PLEASE can some one help me out?

Question

Question 20 (Multiple Choice Worth 4 points)

Factor the polynomial x2 + 6x – 27. Which one of the following is a factor?

(x – 9)

(x + 3)

(x + 9)

(x + 6)



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Question 21 (Multiple Choice Worth 4 points)

Factor the polynomial 15x – 3xy + 20 – 4y by grouping.

3(5x – 3y) + 4(5 – y)

(3x + 4)(5 – y)

(3x – 4)(5 + y)

Prime



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Question 22 (Multiple Choice Worth 4 points)

Solve the given equation by using the quadratic formula.

x2 – 5x – 3 = 0

What value is under the square root (or radical) in your answer? (Note: You are asked to identify only the value under the radical, not the solution to the equation.)

25

9

16

37



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Question 23 (Multiple Choice Worth 4 points)

Factor the polynomial ax + 2ay + bx + 2by by grouping.

(a + x)(b + 2y)

a(x + 2y) + b(x + 2y)

(a + b)(x + 2y)

Prime



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Question 24 (Essay Worth 4.0 points)

Use the following quadratic equation to complete parts a and b below. You must show all work.

x2 + 3x - 18 = 0

a. Solve by factoring.
b. Solve using the quadratic formula.

Question 25 (Multiple Choice Worth 4 points)

Factor the polynomial 12x2 + 11x – 5 completely.

(12x – 5)(x + 1)

(12x + 1)(x – 5)

(4x + 5)(3x – 1)

(4x – 1)(3x + 5)

Answer 1

#20 factors into (x+9)(x-3)

#21 it factors into (3x+4)(5-y)

#22 b^2-4ac=37

#23 (a+b)(x+2y)

#24 by factoring: the factors of 18 that give you 3 are 6 and 3. so it factors into (x+6)(x-3). Set each factor = to 0 and solve. x+6=0 and x-3=0. So x= -6 and 3.

by quadratic formula: x={-3+- sqrt(3^2- 4*1*-18)}/2(1)
x= {-3+-sqrt(81)}/2
x={-3+-9}/2
x=(-3+9)/2 and x=(-3-9)/2
x=6/2 and x=-12/2
x=3 and x=-6

#25 factors into (4x+5)(3x-1)

Answer 2

20. Factor the polynomial x2 + 6x – 27. Which one of the following is a factor?

There are two ways to do this problem: long division and checking for zeroes. You should be able to do both.

There's a reason they teach you long division with numbers: if you understand it with numbers, it's not too big a jump to do it with polynomials. Do a long-division problem, and just forget that you know what "10" means. Try that, and *then* ask something specific about long division of polynomials.

But the easy way to do this problem is to recognize that a linear factor corresponds to a root of the polynomial: if a polynomial is (x + 24)(whatever), and (x + 24) is zero, then the polynomial is zero. So if you want to know whether (x + 24) is a factor, just plug in -24 for x. Or in this case, plug in 9, -3, -9, and -6.

21. Factor the polynomial 15x – 3xy + 20 – 4y by grouping.

Well, the first one isn't a factorization. It's an expression that's of the right form to be a step in the process of factoring it by grouping, but it isn't.

First group together some terms that have something in common. The first two terms have a factor of 3x in them, and the last two terms have a factor of 4y.

15x – 3xy + 20 – 4y = 3x(5 - y) + 4(5 - y)

Then lo&behold the leftovers are the same, because the example was contrived that way. If you can't finish it from there, get help.

And as I said -- Ask fewer of these in each question, then try to understand how people got the answers, then ask again about what you don't understand. Having the answers is worthless. Understanding how to get the answers is priceless. So quit trying to get people to give you the answers.

Answer 3

#20 (x - 3)(x + 9)

#21 (3x + 4) (5 - y)

#22 37

#23 (a + b)(x + 2y)

#24 a) x2 + 3x -18 =0
x2 + (6 - 3)x - 18 =0
x2 + 6x - 3x - 18 =0
x(x + 6) -3 (x + 6)=0
(x - 3)(x + 6)=0

b) x= -b +- sqrt b2 - 4ac / 2a
x= -3 +- sqrt 9 - 4 *1(-18) / 2 * 1
x= -3 +- sqrt 9 + 72 / 2
x= -3 +- sqrt 81 / 2
x = -3 +- 9 / 2

Taking + sign x1= -3 +9 / 2= 6/2 = 3
Taking - sign x2 = -3 -9 / 2 = -12/2 = -6

# 25 12x2 + 11x - 5
=12x2 + (15 -4)x - 5
=12x2 + 15x - 4x - 5
= 3x (4x + 5) - (4x + 5)
=(3x - 1)(4x + 5)

Answer 4

20 (x-9)(x+3)
21 (3x + 4)(5 – y)
22 Don't know I would have said 2
23 a(x + 2y) + b(x + 2y)
24 x= -6 or +3
25 (4x + 5)(3x – 1)

Answer 5

For almost all of them you can use the quadratic formula:
http://en.wikipedia.org/wiki/Quadratic_equation
On this site you can find the formula.

20) C

21) B

22) D

23) C

24) factor it into 2 binomials:
(x+6) and (x-3)
then set them equal to zero:
(x+6) =0
(x-3) =0
Solve for x:
Subtract 6 on both sides to get x=6
Add 3 on both sides to get x=3.

To get the answer using the quadratic formula, just plug the numbers in their corresponding places. Plug in the values:
a=1
b=3
c= (-18)
You should get the same values of x as above.

25) This problem should be easy if you plug it into the quadratic equation. Plug in the values:
a=12
b=11
c=(-5)
Your answer should be C.

Hope this helps!

Answer 6

1)x^2+6x-27
=x^2-3x+9x-27
=x(x-3)+9(x-3)
=(x-3)(x+9) so x+9
2) sq rt{5^2-4(1)(-3) }
=sq rt(25+12)
=sq rt(37) so 37
3) ax+2ay+bx+2by
=a(x+2y)+b(x+2y)
=(a+b)(x+2y) ans
4)x^2+3x-18=0
or x^2-3x+6x-18=0
or x(x-3)+6(x-3)=0
or (x-3)(x+6)=0 so x=3 or x=-6
ii)[-3+- sq rt{3^2-4.1.(-18)}]/2
=[-3+-sq rt(9+72)}/2
=[-3+-sq rt(81)]/2
or {-3+-9}/2
or 6/2 or -12/2
or 3 or -6 ans
5) 12x^2+11x-5
=12x^2-4x+15x-5
=4x(3x-1)+5(3x-1)
=(3x-1)(4x+5) ans

Answer 7

Get off the Internet, crack the book, and learn how to factor polynomials.

Answer 8

hAHAHA brilliant, making someone else do your homework! I wonder how you'll feel 10 years from now when you're bagging groceries though.