Question

（a-1）的平方+a(1-a),其中a=根号2再-1

Answer 1

（a-1）^2+a(1-a)

=(a-1)^2-a(a-1)

=(a-1-a)(a-1)

=-(a-1)

=1-a

=1-√2+1

=2-√2