Question

спрости вираз 5(-1,4+3)-(1-2,5x)-4(0,8x+3)=, якщо x=5/7

Answer 1

Ответ:

$5( - 1.4 + 3) - (1 - 2.5x) - 4(0.8x + 3) = - 7 + 15 - 1 + 2.5x - 3.2x - 12 = - 0.7x - 5 \: \: \: \: \: x = \frac{5}{7} \\ - 0.7 \times \frac{5}{7} - 5 = - \frac{7}{10} \times \frac{5}{7} - 5 = - \frac{1}{2} - \frac{5}{1} = \frac{1 - 10}{2} = - \frac{9}{2} = - 4 \frac{1}{2} = - 4.5$