How do I get:

12(x-4)-(x+2)=(x+2)(x-4)

into quadratic standard form? I have the answer for what the standard form is for this, I just have no clue how they got it. Book is fail.

Question

How do I get:

12(x-4)-(x+2)=(x+2)(x-4)

into quadratic standard form? I have the answer for what the standard form is for this, I just have no clue how they got it. Book is fail.

anonymous · Answer

standard form is $$x ^{2}-13x+42=0$$ if anyones wondering

chaise · Answer

12(x-4)-(x+2)=(x+2)(x-4)
Let's start by expanding the brackets?
(12x-48)-(x+2)=(x+2)(x-4)
11x-50=(x+2)(x-4)
Let's foil out the right hand side?
11x-50=x^2-2x-8
Minus 11x both sides, plus 50. both sides.
x^2-13x+42=0

Too easy?

anonymous · Answer

thank you for explaining. Book just threw it at me without any explination