Question

下列因式分解正确的是a:1+4x^2=(1+2x)^2, b:6a-9-a ^2=-(a-3)

2,c:1+4m-4m ^2,d:x ^2+xy+y ^2=(x+y) ^2

Answer 1

对的是b:
6a-9-a ^2=-(a^2-6a+9)=-(a-3)^2

Answer 2

b:6a-9-a ^2=-(a-3)^2

Answer 3

d