1.

If for all real values of a one root of the equation `x^2-3ax + f(a)=0` is double of the other, then f(x) is equal toA. `2x`B. `x^(2)`C. `2x^(2)`D. `2sqrt(x)`

Answer» Correct Answer - C
Let `alpha` beone of
`x^(2)-3ax+f(a)=0`
`impliesalpha+2alpha=3alphaimplies3alpha=3a`
`impliesalpha=a` …………i
and `alpha.2alpha=f(a)`
`impliesf(a)=2alpha^(2)=2alpha^(2)` [ using Eq. (i)]
`impliesf(x)=2x^(2)`


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