Answer
$p=36$
Work Step by Step
The given equation is
$\Rightarrow \sqrt p-7=-1$
Add $7$ to each side.
$\Rightarrow \sqrt p-7+7=-1+7$
Simplify.
$\Rightarrow \sqrt p=6$
Square each side of the equation.
$\Rightarrow (\sqrt{p})^2=6^2$
Simplify.
$\Rightarrow p=36$
Check $p=36$.
$\Rightarrow \sqrt p-7=-1$
$\Rightarrow \sqrt {36}-7=-1$
$\Rightarrow \sqrt {6^2}-7=-1$
$\Rightarrow 6-7=-1$
$\Rightarrow -1=-1$
True.
Hence, the solution is $p=36$.
