y=x2–3x+2
⇒y=(x–1)(x–2)
At x-axis y=0
⇒x=1,2
So this curve intersects the x-axis
at A(1, 0) and B(2, 0).
dxdy=2x−3
(dxdy)x=1=−1 and (dxdy)x=2=1
Equation of tangent at A(1, 0) :
y=–1(x–1)
⇒x+y=1
and equation of tangent at B(2, 0):
y=1(x–2)
⇒x–y=2
So
a=1 and
b=2
⇒ba=0.5