tham khảo tại:https://hoc24.vn/hoi-dap/tim-kiem?q=Cho+%C4%91a+th%E1%BB%A9c+f+(x)+=+ax3+bx2+cx+dax%5E3+bx%5E2+cx+d++v%E1%BB%9Bi++a+l%C3%A0+s%E1%BB%91+nguy%C3%AAn+d%C6%B0%C6%A1ng+.+Bi%E1%BA%BFt+f+(5)+-+f+(+4+)+=2012+.++Ch%E1%BB%A9ng+minh+f+(7)+-+f+(2)+l%C3%A0+h%E1%BB%A3p+s%E1%BB%91+.&id=249516

chịu

C

Câu C

câu c

Bài 4:

\(f\left(x\right)+x.f\left(-x\right)=x+1\) (*)

Thay \(x=1\) vào (*), ta có:

\(f\left(1\right)+1.f\left(-1\right)=1+1\Rightarrow f\left(1\right)+f\left(-1\right)=2\) (**)

Thay \(x=-1\) vào (*), ta có:

\(f\left(-1\right)+\left(-1\right).f\left(-\left(-1\right)\right)=-1+1\Rightarrow f\left(-1\right)-f\left(1\right)=0\) (***)

Trừ (**) và (***) vế theo vế, ta có:

\(\left(f\left(1\right)+f\left(-1\right)\right)-\left(f\left(-1\right)-f\left(1\right)\right)=2-0\)

\(\Rightarrow f\left(1\right)+f\left(-1\right)-f\left(-1\right)+f\left(1\right)=2\)

\(\Rightarrow\left(f\left(1\right)+f\left(1\right)\right)+\left(f\left(-1\right)-f\left(-1\right)\right)=2\)

\(\Rightarrow2.f\left(1\right)=2\)

\(\Rightarrow f\left(1\right)=1\)

MK..........................................................................................ngu hóa

bắt tay nào =.= 

kb ik có j giúp đỡ nhau môn hóa...

<bắt tay>

Would you be so kind to help me with my English?