
The given equations are,
{y}^{2}=4x & x+y=1
⇒y2=4(1−y)
⇒y2+4y−4=0⇒y=22−2
∴ Required Area =∫022−2[(1−y)−4y2]dx=(y−2y2−12y3)022−2
=[(22−2)−2(22−2)2−12(22−2)3−0]
=(22−2)[1−(2−1)−3(2−1)2]=−310+382
⇒−310+382=a2+b⇒a=38,b=−310
∴a−b=38+310=6