1. 2у + у(3 – (у + 1)) = у(2 – у) + 12
2у + у(3 – у - 1) = 2y - y² +12
2у + 3y - y² - y = 2y - y² +12
2у + 3y - y² - y - 2y + y² = 12
2y = 12
y = 12 : 2
y = 6
2. 7 + 3(- х – 3(х + 5)) = 5(7 –
2х) + х
7 + 3(- х – 3х - 15) = 35 - 10x + x
7 - 3x - 9x - 45 = 35 - 10x + x
10x - x - 3x - 9x = 35 - 7 + 45
-3x = 73
-x = 73 : 3
-x ≈ 24,3
x ≈ - 24,3