Q59 / 90 · JEE Main 2022 (25 Jul Shift 2) · Mathematics

Let the area enclosed by the x-axis, and the tangent and normal drawn to the curve 4x3-3xy2+6x2-5xy-8y2+9x+14=0  at the point -2,3 be A. Then 8A is equal to _______.

Correct answer: 170

Solution

The given curve is 4x3-3xy2+6x2-5xy-8y2+9x+14=0 

On differentiating both sides, we get

12x2-3y2-6xyy'+12x-5y-5xy'-16yy'+9=0

Now, at the point -2,3

48-27+36y'-24-15+10y'-48y'+9=0

i.e. y'-2,3=-92

So slope of tangent  mT=-92 and 

slope of normal mN=29

i.e. equation of tangent T≡y-3=-92x+2⇒y=-92x-6

and equation of normal N≡y-3=29x+2⇒y=29x+319

Intersection point of tangent and normal is -2,3

The intersection point of tangent and normal with x-axis respectively will be -43,0 & -312,0

Now, area of triangle formed =12×Base×Height

A=12×-43+3123=12856·3=854

⇒8A=170

Hence, the correct answer is 170.

Relevant Questions