Question

已知a=13/19,b=-1/4,求(a+b)^2-2(a^2-b^2)+(b-a)^2的值急急急急急

Answer 1

a=13/19,b=-1/4,

(a+b)^2-2(a^2-b^2)+(b-a)^2

=(a+b)^2-2(a+b)(a-b)+(a-b)^2

=[(a+b)-(a-b)]^2

=(2b)^2

=4b^2

=4*(-1/4)^2

=4*(1/16)

=1/4.