Solve: $ b = 12/a $, substitute: $ a^2 - (144/a^2) = -64 $. Multiply by $ a^2 $: $ a^4 + 64a^2 - 144 = 0 $. Let $ u = a^2 $: $ u^2 + 64u - 144 = 0 $. - Veritas Home Health