(2) The original formula = (2+3a) (2-3a);

(3), the original formula = (x+y+z) (x+y-z);

(4), the original formula = (a+b-c) (a-b+c);

Question 22: (1), the original formula = (217+17) (217-17) =/kloc.

(2) The original formula = (3.25+6.75) (3.25-6.75) =-3.5 *10 =-35;

23. The original formula = (x+y) (x-y) = (-4) * 8 =-32;