Q5 / 40 · NTA Abhyas (JEE Main) 2020 · Mathematics · Hyperbola

The sum of the y-intercepts of the tangents drawn from the point -2,-1 to the hyperbola x23-y22=1 is

Correct answer: 6

Solution

Let, the equation of the tangent from -2,-1 is y=mx+3m2-2
⇒-1=-2m+3m2-2
⇒2m-12=3m2-2
⇒m2-4m+3=0
⇒m=1,3
So, the equations of the tangents are
y+1=x+2 & y+1=3x+2
⇒y-intercepts of the tangents are 1 & 5
⇒ the sum of y-intercepts =6

Hence, the correct answer is 6.

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