Question

1/(x^2-1)怎么因式分解

因式分解后 y=1/2[(1/(x-1)-1/(x+1)] 这个怎么得的

Answer 1

1/(x^2-1)
=1/（x+1）（x-1）
=1/2【（x+1）+（x-1）】/（x+1）（x-1）
=1/2【1/（x-1）+1/（x+1）】

Answer 2

1/(x^2-1)
=1/（x+1）（x-1）
=1/2[（x+1）-（x-1）]/（x+1）（x-1）
=1/2[1/（x-1）-1/（x+1）]

Answer 3

x²+6xy+9y²-9a²+6a-1
=(x²+6xy+9y²)-(9a²-6a+1)
=(x+3y)²-(3a-1)²
=[(x+3y)+(3a-1)][(x+3y)-(3a-1)]
=(x+3y+3a-1)(x+3y-3a+1)