NTA Abhyas JEE Main2020MathematicsEllipsePractice
If m 1 and m 2 are the slopes of the tangents to the ellipse x 2 16 + y 2 9 = 1 which passes through 5,4 , then the value of m 1 + m 2 - m 1 m 2 is equal to
Options
- A47 9
- B- 40 9
- C22 3
- D11 3
Correct answer
D. 11 3
Step-by-step solution
Let the equation of tangent passing through 5,4 is y = m x ± 16 m 2 + 9 ⇒ 4 = 5 m ± 16 m 2 + 9 ⇒ 4 - 5 m 2 = 16 m 2 + 9 ⇒ 9 m 2 - 40 m + 7 = 0 ⇒ m 1 + m 2 = 40 9 , m 1 m 2 = 7 9 ⇒ m 1 + m 2 - m 1 m 2 = 33 9 = 11 3