Q. If one root of the equation `x^2-3ax+f(a)=0` is double of the other,then `f(x)` =? A) `2x` B) `x^2` C) `2x^2` D) `x`
Let one of the roots of the equation `x^2-3ax+f(a)` be p, and the other root is 2p.
Then the equation can be written as: `(x-p)(x-2p)=0`
Comparing the coefficient of `x` , we get
Again, comparing the constant term,
Hence option C) is correct.