\(f\left(x\right)=x^6-10x^5+10x^4-10x^3+10x^2-10x+10\)
\(f\left(x\right)=x^5\left(x-10\right)+x^3\left(x-10\right)+x\left(x-10\right)+10\)
\(f\left(x\right)=\left(x-10\right)\left(x^5+x^3+x\right)+10\)
\(f\left(x\right)=x\left(x-10\right)\left(x^4+x^2+1\right)+10\)
\(\Rightarrow f\left(9\right)=9.\left(9-10\right)\left(9^4+9^2+1\right)+10\)
\(\Leftrightarrow f\left(9\right)=9.\left(-1\right).\left(6643\right)+10\)
\(\Leftrightarrow f\left(9\right)=-59777\)
P/s : làm cho zui thôi nha , sai đừng đáp đá
\(x=9\)\(\Rightarrow x+1=10\)
\(\Rightarrow f\left(9\right)=x^6-\left(x+1\right)x^5+\left(x+1\right)x^4-\left(x+1\right)x^3+\left(x+1\right)x^2-\left(x+1\right)x+\left(x+1\right)\)
\(=x^6-x^6-x^5+x^5+.......-x+x+1=1\)
