Объяснение:

[tex]1)2 {x}^{4} - {x}^{4} + 7 {x}^{2} - 4 x^{2} - 5x + x = {x}^{4} + 3 {x}^{2} - 4x \\ 2 ^{4} + 3 \times 2 ^{2} - 4 \times 2 = 16 + 12 - 8 = 20 \\ 2)0.4 b ^{3} - 0.3 b ^{3} - 0.2 {b}^{2} + 0.5b - 0.5b + 7 = 0.1b ^{3} - 0.2b ^{2} + 7 = 0.1 \times (- 2^{3} ) -0.2 \times ( - 2 ^{2} ) + 7 = 0.1 \times ( - 8) - 0.2 \times 4 + 7 = - 0.8 - 0.8 + 7 = - 1.6 + 7 = 5.4 \\ 3) - 4 {a}^{2} b + 3 {a}^{2} b + 5a^{2}b + 3ab^{2} - 5a {b}^{2} = 4a^{2} b - 2a {b}^{2} = 4 \times 25 \times ( - 0.4) - 2 \times 5 \times 0.16 = - 40 - 1.6 = - 41.6 \\ 4) - 0.3x - 24xy^{2} = - 0.3 \times 4 - 24 \times 4 \times ( - 0.2^{2} ) = - 1.2 - 3.84 = - 5.04[/tex]