1)
10(x+4)=9x
10x+40=9x
10x-9x=-40
x=-40
2)
3(-7-3x)=10x-2
-21-9x=10x-2
-9x-10x=-2+21
-19x=19
x=19:(-19)
x=-1
<span>−12 ≤ x < 13, −9 < y ≤ 6
-12-9</span>≤ <span>x+y </span>≤13+6
-21 ≤ x+y ≤ 19-12-(-9) ≤x-y ≤ 13-6
-3≤ x-y ≤ 7
<span>(а-4)^2 -2а(3а-4)=a^2 - 8a + 16 - 6a^2 + 8a = -5a^2 + 16
-5*(-1)^2 + 16 = -5 + 16 = 11</span>