You didn't specify the topic so I will solve it in 3 topics solving for a, you take roots of both sides and solve a=18,-18 using the quadratic formula, solve the equation for aa by finding aa, bb, and ccof the quadratic then applying the quadratic formula.
a=±√321a=±321
a≈17.91647286,−17.91647286
for factoring, Factor and set each factor equal to zero.