SOLUTION: I am totally confused by the factoring results my text says is the answer: The equation is 3x^2 + x - 2 = 0 They say the factor of this is (3x - 2)(x + 1) Why isn't it -

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: I am totally confused by the factoring results my text says is the answer: The equation is 3x^2 + x - 2 = 0 They say the factor of this is (3x - 2)(x + 1) Why isn't it -      Log On


   

Question 395314: I am totally confused by the factoring results my text says is the answer: The equation is
3x^2 + x - 2 = 0
They say the factor of this is
(3x - 2)(x + 1)
Why isn't it -1, +2? Isn't the product of -2 suppose to equat the sum of 1 ?
Please show me why their answer is correct? I even tried using the ac Method with no results.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

3x^2 + x - 2 = 0   |After factoring, the factors must represent the original

factoring to a product (__ ±  __)(  ±  __) Note: 2*-1 = -2 or -2*1 = -2

 (3x ±  __)(x  ±  __)   |3x and x need to be in the 1st spots

 (3x ±  __)(x  ±  __)   | 2 and 1 need to go into one or the other of 2nd spot blanks

 (3x -2)(x+1)=0        |this arrangement works for the + and - using the 2 and 1

 Noting: The SUM of the inner product(-2x) and the outer product(3x) = x



CHECKING our Answer

 3x(x+1) - 2(x+1) = 3x^2 + 3x - 2x - 2 = 3x^2 + x - 2



 (3x -2)(x+1)=0    | x = 2/3 or x = -1