Question

Calcule o valor numérico de: 2x³- 4x² + x - 1 para:

a) x = 0;

b) x = -1

c) x = ½

d) x = -⅓​

Answer 1

2x³- 4x² + x - 1

a) x = 0

2x³- 4x² + x - 1

2*0³- 4*0² + 0 - 1

0 - 0 + 0 - 1

-1

b) x = -1

2(-1)³- 4(-1)² + (-1) - 1

2*(-1) - 4 - 2

-2 - 4 - 2

-8

c) x = ½

2(½)³- 4(½)² + (½) - 1

2*1/8 - 4*1/4 + (½) - 1

2/8 - 4/4 + (½) - 1

1/4 - 1 + (½) - 1

- 2 + 1/4 + (½)

-2 + 3/4

-1 1/4 = -5/4

d) x = -⅓

2( -⅓)³- 4( -⅓)² + ( -⅓) - 1

2 (-1/27) - 4(1/9)  - 4/3

-2/27 - 4/9 - 4/3

(-2 - 12 - 36)/27

-50 / 27