Question

一些二次根式题1.各式中从左到右变形正确的是：a.a√(ab)=√(a^3b)b.(a+b)√(a+b)=√(a+b)^

Answer 1

1.a√(ab)=√a^2*√(ab)=a^2*√[a^2*(ab)]

=√(a^3b)

2.(a+b)√(a+b)=√(a+b)^2*√(a+b)=√[(a+b)^2*(a+b)]=√(a+b)^3

3.√[(x^2+y^2)^2-(x^2-y^2)^2]

=√{[(x^2+y^2)+（x^2-y^2）]*[(x^2+y^2)-（x^2-y^2)]}

=√(2x^2*2y^2)

=正负2xy