Question

下列各多项式中,能在有理数范围内因式分解的是 A.x^2+4x-4 B.a^2-8b^2 C.x^2-x+1/4 D.x

Answer 1

A.x^2+4x-4

=.x^2+4x+4-8

=(x+2)^2-8

=(x+2+2√2)(x+2-2√2)

B.a^2-8b^2

=(a+2√2b)(a-2√2b)

C.x^2-x+1/4

=(x-1/2)^2

D.x^2+9y^2

选C