Solve: t2+2t+1=0
We have, t2+2t+1=0
⇒t2+t+t+1=0
⇒t(t+1)+1(t+1)=0
⇒(t+1)(t+1)=0
⇒(t+1)=0or,(t+1)=0
⇒t=−1or,t=−1