1.(9х-7)(8х+5) 2.модуль 5х-7 =9 3.7-2(9х-4)=9+7(5х-3) - вопрос №1978525793729497533801189 от простоhhh 12.09.2021 08:14

Question

Математика: 1.(9х-7)(8х+5) 2.модуль 5х-7 =9 3.7-2(9х-4)=9+7(5х-3)

простоhhh · Answer

1. (9х-7)(8х+5)=72х²+45х-56х-35=72х²-11х-35
2. l5х-7l=9
5х-7=9 или 5х-7=-9
5х=16 5х=-2
х=3,2 х=-0,4
3.7-2(9х-4)=9+7(5х-3)
7-18х+8=9+35х-21
-18х-35х=9-21-7-8
-53х=-27
х= $\frac{27}{53}$