$a)x^2-49=0$

$\left(x-7\right)\left(x+7\right)=0$

$x-7=0lubx+7=0$

$x=7lubx=-7$

 

 

$b)x^2-144=0$

$\left(x-12\right)\left(x+12\right)=0$

$x-12=0lubx+12=0$ $x-12=0lubx+12=0$

$x=12lubx=-12$

 

 

$c)9x^2-1=0$

$\left(3x-1\right)\left(3x+1\right)=0$

$3x-1=0lub3x+1=0$

$3x=1lub3x=-1$

$x=\frac{1}{3}lubx=-\frac{1}{3}$

 

 

$d)36x^2-1=0$

$\left(6x-1\right)\left(6x+1\right)=0$

$6x-1=0lub6x+1=0$

$6x=1lub6x=-1$

$x=\frac{1}{6}lubx=-\frac{1}{6}$

 

 

$e)4x^2-81=0$

$\left(2x-9\right)\left(2x+9\right)=0$

$2x-9=0lub2x+9=0$

$2x=9lub2x=-9$

$x=\frac{9}{2}=4\frac{1}{2}lubx=-\frac{9}{2}=-4\frac{1}{2}$

 

 

$f)25x^2-36=0$

$\left(5x-6\right)\left(5x+6\right)=0$

$5x-6=0lub5x+6=0$

$5x=6lub5x=-6$

$x=\frac{6}{5}=1\frac{1}{5}lubx=-\frac{6}{5}=-1\frac{1}{5}$