А)4х-12=18-х;б) 21х-5(2х-7)=24;в)0,15(х-4)=9,9-0,3(х-1)

Question

А)4х-12=18-х;
б) 21х-5(2х-7)=24;
в)0,15(х-4)=9,9-0,3(х-1)

Answer 1

а) 4х - 12 = 18 - х             б) 21х - 5(2х - 7) = 24

4х + х = 18 + 12                21х - 10х + 35 = 24

5х = 30                              11х = 24 - 35

х = 30 : 5                           11х = - 11

х = 6                                   х = - 11 : 11

                                           х = - 1

в) 0,15(х - 4) = 9,9 - 0,3(х - 1)

0,15х - 0,6 = 9,9 - 0,3х + 0,3

0,15х + 0,3х = 9,9 + 0,3 + 0,6

0,45х = 10,8

х = 10,8 : 0,45

х = 24