已知f{x}=2sin x + x³ +1 ,若f{a}=3,则f{-a}=?

已知f{x}=2sin x + x³ +1 ,若f{a}=3,则f{-a}=?
已知f{x}=2sin x + x³ +1 ,若f{a}=3,则f{-a}=?

已知f{x}=2sin x + x³ +1 ,若f{a}=3,则f{-a}=?
f{-x}=2sin（- x ）+ （-x）³ +1
=-2sinx-x³ +1
=-（2sin x + x³ +1 ）+2
=-f{x}+2
f{a}=3,则
f{-a}=-f{a}+2=-3+2=-1
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f{x}=2sin x + x³ +1
f{a}=2sin a + a³ +1=3,
2sin a + a³=2
f{-a}= -2sin a - a³+1=-2+1=-1

已知f{x}=2sin x + x³ +1 ，若f{a}=3
即
2sina＋a³＋1=3
2sina＋a³=2
所以
f(-a)=2sin(-a)+(-a)³＋1
=-(2sina＋a³)+1
=-2+1
=-1