Question

Найдите значение выражения 18 xy- 2y+ 9y - 1 если x=5, y= -0,7СРОЧНО

Answer 1

Здравствуйте!
1 способ решения.

$18 \times 5 \times ( - 0.7) - 2 \times ( - 0.7) + 9 \times ( - 0.7) - 1 = \\ = 90 \times ( - 0.7) + 1.4 - 6.3 - 1 = \\ = - 63 + 1.4 - 6.3 - 1 = \\ = - 61.6 - 6.3 - 1 = \\ = - 67.9 - 1 = \\ = - 68.9$
2 способ решения.
$18xy - 2y + 9y - 1 = \\ = 18xy + 7y - 1$
$18 \times 5 \times ( - 0.7) + 7 \times ( - 0.7) - 1 = \\ = 90 \times ( - 0.7) - 4.9 - 1 = \\ = - 63 - 4.9 - 1 = \\ = - 67.9 - 1 = \\ = - 68.9$
Ответ: -68.9