How do you factor the quadratic $x^2-121$ ?

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Answer 1 · 2018-04-30T04:40:16

$x^2-121=(x+11)(x-11)$

As $x^2$ and $121=11^2$ are both squares of $x$ and $11$ and there is minus sign between their squares,

we can use the identity $a^2-b^2=(a+b)(a-b)$

observe that factors of difference of squares $a^2$ and $b^2$ are sum of $a$ and $b$ and difference of $a$ and $b$

and then factors are sum of $x$ and $11$ and difference of $x$ and $11$

i.e. $x^2-121=(x+11)(x-11)$

How do you factor the quadratic x^2-121x^2-121?