1.

A polynomial function f(x) satisfies the condition `f(x)f(1/x)=f(x)+f(1/x)` for all `x inR`,`x!=0`. If f(3)=-26, then f(4)=A. `-35`B. `-63`C. 65D. none of these

Answer» Correct Answer - B
We know that a polynomial function f(x) of degree n satisfying.
`f(x)f((1)/(x))= f((1)/(x)) ` for all `x(ne0) in R`is of the form
`f(x) = 1 pm x^(n) ` for all `x (ne 0) in R`.
We are given that f(3) =- 26.
`therefore f(x) = 1 - x^(n)" ".....(i)`
`rArr f(3) = 1- 3^(n)`
`rArr -26= 1-3^(n)" "[becausef (3) = - 26]`
`rArr 3^(n) = 27 rArr 3^(n) = 3^(3) rArr n = 3`
Substituting n = 3 in (i), we get
`f(x) = 1-x^(3) rArr f(4) = 1-4^(3) = - 63`


Discussion

No Comment Found

Related InterviewSolutions