Question

Tính GTBT tại x=14   :    A=x⁵-15x⁴+16x³-29x²+13x

Answer 1

x=14

=>15=x+1

    16=x+2

     29=x+15

     13=x-1

=>A=x⁵-15x⁴+16x³-29x²+13x

=x⁵-(x+1)x⁴+(x+2)x³-(x+15)x²+(x-1)x

=x⁵-x⁵-x⁴+x⁴+2x³-x³-15x²+x²-x

=x³-14x²-x

=x³-x.x²-x

=x³-x³-x

=-x

=-14

Vậy A=-14

Answer 2

x=14

=>15=x+1

    16=x+2

     29=x+15

     13=x-1

=>A=x⁵-15x⁴+16x³-29x²+13x

=x⁵-(x+1)x⁴+(x+2)x³-(x+15)x²+(x-1)x

=x⁵-x⁵-x⁴+x⁴+2x³-x³-15x²+x²-x

=x³-14x²-x

=x³-x.x²-x

=x³-x³-x

=-x

=-14

Vậy A=-14