4(3-0,5х)+11,5х=50 х²-3х+12=0 2х²+10х=0 20-5х²=0

4(3-0,5х)+11,5х=50
12-2х+11,5х = 50
9,5х = 50-12
9,5х=38
х = 38:2,5
х = 15,2
х²-3х+12=0
D = 9-48 = -39
корней нет
2х²+10х=0
х*(2х+10) = 0
х = 0
2х+10 = 0
2х = -10
х = -5
20-5х²=0
-5х² = -20
х² = 4
х = 2
х = -2