How do you FOIL $(x - 10) (x + 10)$ $(x-10)(x+10)$ ?

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Answer 1 · 2018-03-05T05:52:58

$x^{2} - 100$ $x^2-100$

FOIL stands for First, Outside, Inside, Last

multiply the First terms
$x \cdot x = x^{2}$ $x*x=x^2$

multiply the Outside terms
$x \cdot 10 = 10 x$ $x*10=10x$

multiply the Inside terms
$- 10 \cdot x = - 10 x$ $-10*x=-10x$

multiply the Last terms
$- 10 \cdot 10 = - 100$ $-10*10=-100$

add all of the answers together
$x^{2} + 10 x - 10 x - 100$ $x^2+10x-10x-100$

combine like terms
$x^{2} + 10 x - 10 x - 100$ $x^2+color(red)(10x-10x)-100$
$= x^{2} - 100$ $=x^2-100$

How do you FOIL (x-10)(x+10)(x−10)(x+10)(x-10)(x+10)?