1. **State the problem:** Simplify the expression $$(a+b)^2 - 3(2b - a)$$. 2. **Recall formulas and rules:** - The square of a binomial: $$(a+b)^2 = a^2 + 2ab + b^2$$. - Distribute multiplication over subtraction: $$-3(2b - a) = -3 \times 2b + (-3) \times (-a)$$. 3. **Expand the square:** $$ (a+b)^2 = a^2 + 2ab + b^2 $$ 4. **Distribute the -3:** $$ -3(2b - a) = -6b + 3a $$ 5. **Combine all terms:** $$ a^2 + 2ab + b^2 - 6b + 3a $$ 6. **Final simplified expression:** $$ a^2 + 2ab + b^2 + 3a - 6b $$ This is the simplified form of the given expression.