Algebra 1 Question

Question

If (x−2)(x−a) multiplies to x^2 −6x+8, then which of the following is the value of a.

Does A equal 4, 6, -4 or -6

Answer 1

(x−2)(x−a) = x^2-ax-2x+2a= x^2 −6x+8

-ax-2x+2a=−6x+8

-ax+4x+2a=8

Without a value for "a"; I don't know.

Answer 2

You'll need to factor x^2 - 6x + 8 by looking for two numbers that multiply to 8 and also add to be -6. (we already know one number must be -2 based on the first binomial factor)

-2 * __ = 8 and -2 + __ = -6 (Find the missing value, both missing values must be the same number)

So,

-2 * -4 = 8 and -2 + -4 = -6

Therefore,

(x - 2)(x - 4) = x^2 - 6x + 8

and your missing value is a = 4