How do you factor completely $a^2 - 121b^2$ ?

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Answer 1 · 2018-06-13T06:07:21

$a^2-121b^2 = (a-11b)(a+11b)$

The difference of sqares identity can be written:

$A^2-B^2 = (A-B)(A+B)$

Given:

$a^2-121b^2$

Note that both $a^2$ and $121b^2 = (11b)^2$ are perfect sqares.

So we can use the difference of squares identity with $A=a$ and $B=11b$ to find:

$a^2-121b^2 = a^2-(11b)^2 = (a-11b)(a+11b)$

Answer 2 · 2018-06-13T06:08:36

Shown below...

Use difference of two squares:

$(A^2-B^2) = (A+B)(A-B)$

$=> ( (a)^2 - (11b)^2 )$

$=> (a+11b)(a-11b)$

How do you factor completely a^2 - 121b^2a^2 - 121b^2?