## Thinking Mathematically (6th Edition)

12$x^{2}$ + 11
18$x^{2}$ + 4 - [6($x^{2}$ - 2) + 5] Step 1: Drop parentheses and multiply 6 with each term and change the sign of each term in parentheses: 6$x^{2}$ - 12 Step 2 Simplify inside brackets: -12+5 = -7 18$x^{2}$ + 4 - [6$x^{2}$ - 7] Step 3 drop brackets and change the sign of each term in brackets 18$x^{2}$ + 4 - 6$x^{2}$ +7 Step 4: Group like terms (18$x^{2}$ - 6$x^{2}$) +(4+7) Step 6: Combine the like terms ( 18$x^{2}$ - 6$x^{2}$) = 12$x^{2}$ So, final solution 12$x^{2}$ + 11