Concept - x−=+( When a negative number [-] multiplies another negative number[-], the sign becomes positive [+]) −x+=− (When a negative number [−] multiplies a positive number [+], the sign becomes negative [−] ) a2=a×a 2y=1−3x2+4x When x=−1, substitute x by -1 2y=1−3(−1)2+4(−1) (−1)2=−1x−1=+1 4(−1)=4x−1=−4 2y=1−3x2+4x ⇒2y=1−3(1)−4 2y=1−3−4 2y=1−7 2y=−6 Divide both sides by 2 to get rid of the 2 multiplying y ⇒y=−6∕2=−3