Posted by **John** on Saturday, December 29, 2012 at 10:27am.

1) 2x²-7x-15

2) 9x²+24x+16

Can you show me all the steps...i don't know how to do it...Thankyou!!:)

- basic algebra -
**bobpursley**, Saturday, December 29, 2012 at 12:11pm
first: add 7x to each side. Then divide both sides by 9

second: subtract 9x+16 from each side. Then divide both sides by 15

- basic algebra -
**John**, Saturday, December 29, 2012 at 1:31pm
we have to factor not solve

- basic algebra -
**Henry**, Saturday, December 29, 2012 at 2:20pm
1. Y = 2x^2-7x-15 = 0.

Use the AC method of factoring:

A*C = 2*-15 = -30 = 1*-30 = 3*-10.

Choose the pair of factors whose sum = B(-7): 3, and -10.

2x^2 + (3x-10x) - 15 = 0.

Group the 4 terms into 2 factorable pairs:

(2x^2-10x) + (3x-15)

2x(x-5) + 3(x-5)

(x-5) is common to both terms. So we factor out(x-5):

(x-5)(2x+3) = 0

x-5 = 0

X = 5.

2x+3 = 0

2x = -3

X = -1.5.

Solution set: X = 5, and -1.5.

2. 9x^2+24x+16 = 0.

The given expression is a perfect square: 9x^2+24x+16 = (3x+4)^2 = 0.

(3x+4)^2 = 0

Take sgrt of both sides:

+-(3x+4) = 0

3x+4 = 0

3x = -4

X = -1 1/3 = -1.33333.

-3x-4 = 0

-3x = 4

X = -1 1/3 = -1.33333.

Solution X = -1.33333, and -1.33333.

Note: The given expression was set to zero, because the solutions are x-intercepts and Y = 0 at the x-intercepts.

- basic algebra -
**Henry**, Saturday, December 29, 2012 at 3:34pm
9x^2+24x+16. Factor only.

9x^2+24x+16 = (3x+4)^2 = (3x+4)(3x+4).

- basic algebra -
**John**, Sunday, December 30, 2012 at 12:30pm
Thankyou so much!!

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