Question 67900
Solve for a:
{{{a^2 + 4a = 45}}} Subtract 45 from both sides.
{{{a^2 + 4a - 45 = 0}}} Solve this quadratic equation by factoring:
{{{(a-5)(a+9) = 0}}} Apply the zero product principle.
{{{a-5 = 0}}} and/or {{{a+9 = 0}}}
If {{{a-5 = 0}}} then {{{a = 5}}}
If {{{a+9 = 0}}} then {{{a = -9}}}

The solutions:
a = 5
a = -9