Ta có: 

\(A=x^8-2017x^7+2017x^6-2017x^5+...+2017x^2-2017x+25\)

\(=\left(x^8-2016x^7\right)+\left(-x^7+2016x^6\right)+...+\left(x^2-2016x\right)-x+25\)

\(=\left(x-2016\right)\left(x^7-x^6+...+x\right)-x+25\)

Thế x = 2016 vào A ta được

\(=\left(2016-2016\right)\left(2016^7-2016^6+...+2016\right)-2016+25=-2016+25=-1991\)

A=1991

Ko biet lam quen cach lam rui hihihi ^,^

\(A=x^7\left(x-2016\right)-x^6\left(x-2016\right)+x^5\left(x-2016\right)-...+x\left(x-2016\right)-\left(x-2016\right)-2016+25=-1991\)

Ta có : x - 1 = 2018 - 1 = 2017 

N = x⁶ - 2017x⁵ - 2017x⁴ - 2017x³ - 2017x² - 2017x - 2017

N = x⁶ - ( x - 1 ).x⁵ - ( x - 1 ).x⁴ - ( x - 1 ).x³ - ( x - 1 ).x² - ( x - 1 ).x - ( x - 1 )

N = x⁶ - x⁶ + x⁵ - x⁵ + x⁴ - x⁴ + x³ - x³ + x² - x² + x - x + 1

N = 1

f(2016)=2016^8 - 2017*2016^7 +2017*2016^6 - 2017*2016^5 +...+2017*2016^2 - 2017*2016+ 2018

=2016^8 -( 2016^8 + 2016) + (2016^7+2016) - (2016^6 + 2016)+....+2016^3+2016 -( 2016^2 + 2016)+2018

=2018

mình đọc chả hiểu gì 

có bạn nào giải chi tiết ra được không

A=x⁸-2016x⁷-x⁷+2016x⁶+x⁶-2015x⁵+....+2017x+x-2016+2018

  =x⁷(x-2016)-x⁶(x-2016)+.....-x(x-2016)+(x-2016)+2018

Do x=2016\(\Leftrightarrow\)x-2016=0

A=2018

x=2016 nên x+1=2017

\(f\left(x\right)=x^{99}-x^{98}\left(x+1\right)+x^{97}\left(x+1\right)-...-x^2\left(x+1\right)+x\left(x+1\right)-1\)

\(=x^{99}-x^{99}-x^{98}+x^{98}+x^{97}-x^{97}+...-x^3-x^2+x^2+x-1\)

=x-1=2015

\(f\left(x\right)=x^{99}-2017x^{98}+2017x^{97}-...+2017x-1\)

\(=x^{99}-2016x^{98}-x^{98}+2016x^{97}+...-x^2+2016x+x-2016+2015\)

\(=x^{98}\left(x-2016\right)-x^{97}\left(x-2016\right)+...-x\left(x-2016\right)+\left(x-2016\right)+2015\)

\(=\left(x^{98}-x^{97}+...-x+1\right)\left(x-2016\right)+2015\)

\(\Rightarrow f\left(2016\right)=2015\)

Vậy...

\(f\left(x\right)=x^{99}-2017^{x^{98}}+2017^{x^{97}}-...+2017x-1\)

\(f\left(2016\right)=2016^{99}-2017.2016^{98}+2017.2016^{97}-...+2017.2016-1\)

\(f\left(2016\right)=2016^{99}-\left(2016+1\right).2016^{98}+\left(2016+1\right).2016^{97}-...+\left(2016+1\right).2016-1\)

\(f\left(2016\right)=2016^{99}-2016^{99}-2016^{98}+2016^{98}+2016^{97}-2016^{97}-2016^{96}+...+2016^2+2016-1\)

\(f\left(2016\right)=2016-1\)

\(f\left(2016\right)=2015\)