Question

easy question easy medal

x^2-16= (x+4)(x-4)

Why can't it be (x+8)(x-2)?

Answer 1

x+8 and x-2 evaluate and multiply not to give 2 terms, but three terms, respectively x^2 + 6x -16, instead of x^2-16.

Answer 2

oh so how am i supposed to know that during these problems is there a specific method?

Answer 3

use the "FOIL" method
multiply the first terms, then the 2 outer terms, then inner, then the last terms

Answer 4

that takes forever tho is there a faster method

Answer 5

Essentially, whenever you're solving quadratics or simplifying them, you have 3 rules. It sure beats simplifying every single term.

a2-b2 = (a-b)(a+b)
a2-2ab+b2 = (a-b)2
a2+2ab+b2 = (a+b)2

You can manually solve (x+8)(x+2) by splitting it up into x(x+2) + 8(x+2). That would give you x2 +2x +8x+16 which gives you x2+6x+16. ;

Answer 6

still kinda confused

Answer 7

do u mean a^2?