Question

因式分解,过程1、（x平方+y平方）（x平方+y平方-4）+4 2、（9a平方+4b平方）平方 3、x+y=-1,x-y

Answer 1

(x^2+y^2)(x^2+y^2-4)+4

=(x^2+y^2)^2-4(x^2+y^2)+4

=(x^2+y^2-2)^2

(9a^2+4b^2)^2

=81a^4+72a^2b^2+16b^4

x^2-y^2

=(x+y)(x-y)

=-1*(-3)

=3