Question

3аb (5a² — 2b²) + 7ab (2b² - 3а²), если a=-1, b = 2;​

Answer 1

Ответ:

Отв.: -52

Пошаговое объяснение:

3аb (5a² — 2b²) + 7ab (2b² - 3а²) = 3ab(5a²) - 3ab(2b²) + 7ab(2b²) - 7ab(3a²) =

= 15a³b-6ab³+14ab³-21a³b = -6a³b+(-6ab³+14ab³) = -6a³b + 8ab³

Если а = -1, b = 2 то

-6*(-1)³*2 + 8*(-1)*2³ = 6*2 + (-8*2³) = 12 - 64 = -52

Answer 2

ответ: -76... нужно полное решение?

3аb (5a² — 2b²) + 7ab (2b² - 3а²) = ab(15a² - 6b² + 14b² - 21a²) = ab( -6a² + 8b²) = ab( -2 ( 3a² - 4b²) ) = -2ab ( 3a² - 4b²)

подставляем.

- 2 × (-1) × 2 × (3 × (-1)² - 4 × 2² ) = -2×(-1) × 2 × (-3 - 2⁴) = -2 × (-1) × 2 × (-19) = -76

Answer 3

To evaluate the expression 3ab(5a² - 2b²) + 7ab(2b² - 3a²) when a = -1 and b = 2, you simply substitute the values of a and b into the expression and perform the calculations step by step.

Given: a = -1 b = 2

Substitute the values into the expression: 3ab(5a² - 2b²) + 7ab(2b² - 3a²) = 3(-1)(2)(5(-1)² - 2(2)²) + 7(-1)(2)(2(2)² - 3(-1)²)

Now perform the calculations within the parentheses: = 3(-1)(2)(5 - 8) + 7(-1)(2)(8 + 3) = -6(-3) + 7(-1)(11) = 18 - 77 = -59

So, when a = -1 and b = 2, the value of the expression is -59.