Answer
a) The red line is $2x^2-8$, and the blue line is the other function.
b) $2x^2-8$, after factoring out a $2$, is the same function as $4x^2-4$.
Work Step by Step
Please see the graphs.
$x^2-4=0$
$x^2-4+4=0+4$
$x^2 =4$
$\sqrt {x^2} = \sqrt 4$
$x=2, -2$
$2x^2-8=0$
$x^2-8+8=0+8$
$2x^2 =8$
$2x^2/2 =8/2$
$x^2 = 4$
$\sqrt {x^2} = \sqrt 4$
$x=2, -2$
