15. Calculation: = [(number 3+ number 2)+ (number 3- number 2)]X[ number 3+ number 2)- (number 3- number 2)]

Simplification: 2 times root number 3 X 2 times root number 2=4 times the square root of 6.

18.b 2+a 2+2ab Simplification of multiplication on both sides: (A+B) 2 brings in the values of a and b, and we can get:10 2 =100.