Question

помоги брат умоляю прошу

Answer 1

Ответ:

$2 {a}^{3} + 3ab - {b}^{2} - 6 {a}^{3} - 7ab + {b}^{2} = - 4 {a}^{3} - 4ab = - 4a \times ( {a}^{2} + b) = - 4 \times( - 2) (( - 2 {)}^{2} + ( - 4.5) = 8 \times (4 - 4.5) = 8 \times ( - 0.5) = - 4$

$0.4 {b}^{3} - 0.2 {b}^{2} + 0.5b - 0.3 {b}^{3} - 0.5b + 7 = 0.1 {b}^{3} - 0.2 {b}^{2} + 7 = 0.1 \times ( - 1.2 {)}^{3} - 0.2 \times ( - 1.2 {)}^{2} + 7 = 0.1 \times ( - 1.728) - 0.2 \times 1.44 + 7 = 0.1728 - 0.288 + 7 = 6.8848$

$\frac{1}{2} a {b}^{2} + \frac{5}{6} ab + \frac{a {b}^{2} }{3} - 0.25ab = \frac{1}{2} a {b}^{2} + \frac{5}{6} ab + \frac{1 }{3}a {b}^{2} - 0.25ab = \frac{5}{6} a {b}^{2} + \frac{5}{6} ab - \frac{1}{4} ab = \frac{5}{6} a {b}^{2} + \frac{7}{12} ab = \frac{5}{6} \times \frac{1}{5} \times {3}^{2} + \frac{7}{12} \times \frac{1}{5} \times 3 = \frac{1}{6} \times 9 + \frac{7}{60} \times 3 = \frac{3}{2} + \frac{7}{20} = \frac{30 + 7}{20} = \frac{37}{20} = 1 \frac{17}{20}$