Question

已知（a+b）^2=10,（a-b）^2=22,求（1）a^2+b^2的值；（2）ab的值

Answer 1

(a+b)^2=a^2+b^2+2ab=10.(1)

(a-b)^2=a^2+b^2-2ab=22.(2)

(1)+(2)得2(a^2+b^2)=32

a^2+b^2=16

(1)-(2)得4ab=-12

ab=-3