Question
Question: The line lx + my + n = 0 will touch the parabola y<sup>2</sup> = 4ax, if...
The line lx + my + n = 0 will touch the parabola y2 = 4ax, if
A
mn = al2
B
lm = an2
C
ln = am2
D
mn = al
Answer
ln = am2
Explanation
Solution
ln + my + n = 0 ̃ y = m−lx−mn
Condition of tangency c = ma ̃ m−n=−l/ma
̃ m−n=−lam ̃ nl = am2