18ав:6а=3в
сначала делишь коэффициенты, затем буквы
-0,42х² - 0,28х + 0,18х +0,12 =0
-0,42х² - 0,1х +0,12 = 0|*100
42х² +10х -12 = 0|:2
21х² +5х -6 = 0
D = 529
x = (-5 +-√529)/42
х₁ = (-5+23)/42 = 18/42=3/7
х₂= (-5-23)/42 = -28/42 = -14/21 = =2/3
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
2a+3ab=0
a(2+3b)=0
1) a=0 и 2+3b- любое число, т.е. b-любое число
а=0 и b-любое число
2) 2+3b=0
3b=-2
b=-2/3 и а-любое число
а-любое число и b=-2/3