1/(1-x²)+1/(x+1)=2 , dla 1-x²≠0 ⇔(1+x)(1-x)≠0 ⇔ (x≠-1 ∧ x≠1 )
1/(1+x)(1-x)+2/(x+1)=2 |·(1+x)(1-x)
1+(1-x)=2(1+x)(1-x)
1+1-1x=2(1-x²)
2-x=2-2x²
2x²-x=0
x(2x-1)=0
x=0 ∨ 2x-1=0|:2
x=0 ∨ x=1/2
x∈{0,1/2}
