Question

已知：a+b=2,ab=1.求a的平方+b的平方,（a-b)的平方.

Answer 1

a²+b²=(a+b)²-2ab

=2²-2*1

=4-2

=2

（a-b)²=(a+b)²-4ab

=2²-4*1

=4-4

=0