Question

f(x)=x¹⁷-2015x¹⁶+2015x¹⁵-2015x¹⁴+...+2015x-1

Tính f(2014)

~~~FIGHTING~~~

Answer 1

x=2014 => x+1 = 2015

f(2014) = x^17 - (x+1)x^16 + ... + (x+1)x -1
= x^17 - x^17 - x^16 + x^16 - x^15 - ... + x^2 + x -1
= x - 1 = 2013

Answer 2

Ta thấy \(x=2014\Rightarrow x+1=2015\)

Ta có: \(f\left(2014\right)=x^{17}-\left(x+1\right)x^{16}+\left(x+1\right)x^{15}-...+\left(x+1\right)x-1\)

                     \(=x^{17}-x^{17}-x^{16}+x^{16}+x^{15}-...+x^2+x-1\)

                     \(=x-1\)(1)

Thay x=2014 vào  (1) ta được:

   \(f\left(2014\right)=2014-1\)

                      \(=2013\)