If x+x−1=11, evaluate x2+x−2.
x+x−1=11
(x+x−1)2=112 [Squaring both the sides]
⇒(x)2+(x−1)2+2(x)(x−1)=121
⇒ x2+x−2+2=121 [∵(x)(x−1)=x0=1]
⇒ x2+x−2=121−2=119