Ответ: а) c = 34; б) x = -1,45; в) x = -2
a) -9 + (c - 31) = -6
c - 31 = -6 + 9
c - 31 = 3
c = 3 + 31
c = 34
б) (x + 1.45) ⋅ (-x) = 0
x + 1.45 = 0 или -x = 0
x = -1.45 или x = 0
в) 2.1 - 3.6x = 9.3
-3.6x = 9.3 - 2.1
-3.6x = 7.2
x = 7.2 / -3.6
x = -2
Ответ: а) c = 34; б) x = -1,45; в) x = -2