How do you solve $49a^2-1=80$ ?

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Answer 1 · 2018-05-02T00:41:11

$a=+-9/7$

$49a^2-1=80$

$49a^2-81=0 rarr$ This is an example of difference of squares

Difference of squares: $a^2-b^2=(a+b)(a-b)$

$(7a+9)(7a-9)=0$

$7a+9=0$

$7a=-9$

$a=-9/7$

$7a-9=0$

$7a=9$

$a=9/7$

How do you solve 49a^2-1=8049a^2-1=80?