)at(2,−1)=22 ∴‌‌ Equation of tangent :y+1=22(x−2) ∴‌‌y=22x−45‌. ‌ Slope of tangent to y=x3−x2+x at point (a,b) =3a2−2a+1 3a2−2a+1=22 3a2−2a−21=0 ∴‌‌a=3‌ or ‌−‌
7
3
Also b=a3−a2+a Then (a,b)=(3,21) or (−‌
7
3
,−‌
151
9
). (−‌
7
3
,−‌
151
9
) does not satisfy the equation of tangent ∴‌‌a=3,b=21 ∴|2a+9b|=195