Question

(14y+21)(1.8-0.3y)=0

Answer 1

(14y + 21) = 0, или  (1.8 - 0.3y) = 0
1) 14y + 21 = 0
    14y = -21
    y = -1.5
2) 1.8 - 0.3y = 0
    18 - 3y = 0
    -3y = -18
    y = 6
Ответ: $y_{1}$ = -1.5;
$y_{2}$ = 6