Question

2х³+х²+3х²-х²+8 при х= 1; -2

Answer 1

${2x}^{3} + {x}^{2} + {3x}^{2} - {x}^{2} + 8 = \\ {2x}^{3} + {3x}^{2} + 8$

$x = 1 \: \: \: \: \: \: {2x}^{3} + {3x}^{2} + 8 = \\ 2 \times {1}^{3} + 3 \times {1}^{2} + 8 = \\ 2 \times 1 + 3 \times 1 + 8 = \\ 2 + 3 + 8 = 13$

$x = - 2 \: \: \: \: {2x}^{3} + {3x}^{2} + 8 = \\ 2 \times {2}^{3} + 3 \times {2}^{2} + 8 = \\ 2 \times 8 + 3 \times 4 + 8 = \\ 16 + 12 \: + 8 = 36$