2b2+(a+b)(a-b)- (a-b)2, where a =-3 and b =.

Analysis: first simplify the formula with square difference and complete square difference, and then substitute the values of a and b into the simplified result for evaluation.

Solution: The original formula =2b2+a2-b2-a2+2ab-b2=2ab.

When a =-3 and b =, the original formula =2×(-3)× =-3.

Comments: Simplification and evaluation of algebraic formulas is a compulsory part of the senior high school entrance examination, which is less difficult, but easy to make mistakes. It requires candidates to have a good ability to calculate numbers and formulas, especially the application of multiplication formulas, which deserves attention.