SOLUTION: Factor completely: x2 – 5x – 14 Factor completely: 3x2 – 2x – 8 Factor completely: 24x2 + 10x – 4

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Question 27450: Factor completely:
x2 – 5x – 14


Factor completely:
3x2 – 2x – 8


Factor completely:
24x2 + 10x – 4

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Hint: You can indicate x-squared by using the "caret", thus: x^2
Factor completely:
1) x%5E2-5x-14
If this trinomial expression factors, the factors will take the form: (x+m)(x+n) where: (m)*(n) = -14 and (m)+(n) = -5
Try m = -7 and n = +2
(2)(-7) = -14 and (2) + (-7) = -5
The factors are: (x-7)(x+2) Check using the FOIL method:
%28x-7%29%28x%2B2%29+=+x%5E2%2B2x-7x-14 = x%5E2-5x-14
2) 3x%5E2-2x-8
If this trinomial expression factors, the factors will take the form: (3x+m)(x+n) where: (m)*(n) = -8 and (m)+(3n) = -2
Try m = 4 and n = -2
(4)*(-2) = -8 and (4)+3(-2) = 4-6 = -2
The factors are: (3x+4)(x-2) Check using the FOIL method:
%283x%2B4%29%28x-2%29+=+3x%5E2-6x%2B4x-8 = 3x%5E2-2x-8
3) 24x%5E2%2B10x-4
This one requires a little more work because of the lager number of possible factors of the coefficient of x^2 (24).
First, list the factor-pairs of 24:
1 X 24 = 24
2 X 12 = 24
3 X 8 = 24
4 X 6 = 24
The choices of factors of the constant term in the given expression are:
1 X -4 = -4
-1 X 4 = -4
2 X -2 = -4
Now you need to select a pair from the first list of factors and a pair from the second list of factors and, through an educated trial-and-error process, combine them to form the factors of the given expression.
I would try 3 and 8 from the first list and 2 and -2 from the second list. Let's see what happens:
%283x%2B2%29%288x-2%29+=+24x%5E2-6x%2B16x-4 = 24x%5E2%2B10x-4 Ok, a lucky(?) guess.