Answer
See answers below
Work Step by Step
a) $m^2-36=0$
$m^2=36$
$m=\pm \sqrt 36$
$m = \pm 6$
There are two solutions, $ \pm 6$
b) $3x^2+15=0$
$3x^2=-15$
$x^2=-5$
There is no real-number solution.
c) $4d^2+16=16$
$4d^2=0$
$d^2=0$
$d=0$
There is one solution, 0.