Question

Очень ! 1. Выполните выражения:
а. 2с (с^2+3с-1)
б. (3а-5)(4а-3)
в. (х+4)(х^2+2х-3)
г. (15х^2у+10ху):5ху
2. Выполните умножение:
0.4b(5b^2-10)(2+b^2)

Answer 1

$2c( {c}^{2} + 3c - 1) = \\ 2c \times {c}^{2} + 2c \times 3c + 2c \times ( - 1) = \\ 2 {c}^{3} + 6 {c}^{2} - 2c$

$(3a - 5)(4a - 3) = \\ 3a \times 4a + 3a \times ( - 3) - 5 \times 4a - 5 \times ( - 3) = \\ 12 {a}^{2} - 9a - 20a + 15 = \\ 12 {a}^{2} - 29a + 15$

$(x + 4)( {x}^{2} + 2x - 3) = \\ x \times {x}^{2} + x \times 2x + x \times ( - 3) + \\ 4 \times {x}^{2} + 4 \times 2x + 4 \times ( - 3) = \\ {x}^{3} + 2 {x}^{2} - 3x + 4 {x}^{2} + 8x - 12 = \\ {x}^{3} + 6 {x}^{2} + 5x - 12$

$(15 {x}^{2} y + 10xy) \div 5xy = \\ 15 {x}^{2}y \div 5xy + 10xy \div 5xy = \\ (15 \div 5) {x}^{2 - 1} {y}^{1 - 1} + (10 \div 5) {x}^{1 - 1} {y}^{1 - 1} = \\ 3x + 2$

$0.4b(5 {b}^{2} - 10)(2 + {b}^{2} ) = \\ 0.4b(5 {b}^{2} \times 2 + 5 {b}^{2} \times {b}^{2} - 10 \times 2 - 10 \times {b}^{2} ) = \\ 0.4b(10 {b}^{2} + 5 {b}^{4} - 20 - 10 {b}^{2} ) = \\ 0.4b(5 {b}^{4} - 20) = \\ 0.4b \times 5 {b}^{4} + 0.4b \times ( - 20)= \\ 2 {b}^{5} - 8b = 2b( {b}^{4} - 4)$