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

1 Answer
Shwetank Mauria
Apr 30, 2018

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

Explanation:

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)#

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