设f(x)=ax7+bx3+cx-5,其中a、b、c为常数,已知f (-7)=7,求f (7)的值.
∵f(x)=ax7+bx3+cx-5,f (-7)=7
∴a(-7)7+b(-7)3-7c-5=7,
∴a77+b73+7c=-12,
而f (7)=a77+b73+7c-5,
将a77+b73+7c=-12代入得,
∴f (7)=-12-5=-17,
答:f (7)的值-17.
设f(x)=ax7+bx3+cx-5,其中a、b、c为常数,已知f (-7)=7,求f (7)的值.
∵f(x)=ax7+bx3+cx-5,f (-7)=7
∴a(-7)7+b(-7)3-7c-5=7,
∴a77+b73+7c=-12,
而f (7)=a77+b73+7c-5,
将a77+b73+7c=-12代入得,
∴f (7)=-12-5=-17,
答:f (7)的值-17.