Question

Solve this equation using an algebraic method: (x + 4)( x - 4) = 9.

Please use your own answer :)

Answer 1

$\star \ (x + 4)( x - 4) = 9.$ 

$\star \ x^2-4^2=9$  $Expand \ the \ given \ equation$ 

$\star$  $x^2-16=9$ 

$\star$  $x^2=9+16$  $Combine \ like \ terms$ 

$\star$  $x^2=25$ 

$\star$  $x= \sqrt{25}= \sqrt{5}$ 

$\star$ $x=5$