6х+(3х-2)=14
8у-(7у-142)=51
(6х+1)(з-2х)+4=-5х-3

1) 6х+(3х-2)=146х + 3х - 2 = 149х = 16х = 16/92) 8у-(7у-142)=518у - 7у + 142 = 51у = -913) (6х+1)(3-2х)+4 = -5х-318х - 12х^2 + 3 - 2х = -5х - 3-12х^2 + 16х + 3 = -5х - 3-12х^2 + 16х + 3 + 5х + 3 = 0-12х^2 + 21х + 6 = 0-4х^2 + 7х + 2 = 04х^2 - 7х - 2 = 0D = 49+32 = 81 = 9^2x1 = 7 - 9 / 8 = -2/8 = -0,25x2 = 7 + 9 / 8 = 2