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If a polynomial function `f(x)`satisfies `f(f(f(x))=8x+21 ,`where `pa n dq`are real numbers, then `p+q`is equal to _______ |
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Answer» Correct Answer - 5 `f(x)` must be linear function. Therefore, `f(x)=px+q` ` :. f(f(x))=pf(x)+q=p(px+q)+q=p^(2)x+pq+q` ` :. f(f(f(x)))=p(p^(2)x+pq+q)+q` ` =p^(3)x+p^(2)q+pq+q` `=8x+21 ` (Given) ` :. P^(3)=8 or p=2` and `p^(2)q +pq+q=21 or q=3` ` :. p+q=5` |
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