Answer
$y=1\text{ or }y=-1$
Work Step by Step
We start with the given equation: $y^2+7=8$
In order to get the term with $y$ by itself, we subtract $7$ from both sides of the equation: $$y^2+7-7=8-7$$$$y^2=1$$To solve the equation $y^2=1$, we must perform the opposite operation of squaring, which is taking the square root, in order to clear the exponent: $$y^2=1$$$$\sqrt {y^2}=\sqrt {1}$$$$y=\pm1$$$$y=1\text{ or }y=-1$$