Question #b434a

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Answer 1 · 2016-12-10T11:52:43

$f (9) = - 15$ $f(9)=-15$

$f (x) = a x^{7} + b x^{5} + c x^{3} - 6$ $f(x)=ax^7+bx^5+cx^3-6$

$f (x) = g (x) - 6$ $f(x)=g(x)-6$

where

$g (x) = a x^{7} + b x^{5} + c x^{3}$ $g(x)=ax^7+bx^5+cx^3$

is an odd function such that $g (x) = - g (- x)$ $g(x)=-g(-x)$

Now if $f (- 9) = g (- 9) - 6 = 3$ $f(-9)=g(-9)-6=3$ then

$f (9) = g (9) - 6 = - g (- 9) - 6$ $f(9)=g(9)-6 = -g(-9)-6$ but

$g (- 9) = 9$ $g(-9)=9$ then

$f (9) = - 9 - 6 = - 15$ $f(9) = -9-6=-15$