0,66: 0,666: 0,667: 0,67 .
(2+с)(2-с)+(с-3)²-3(4+2с)=
=4-с²+с²-6с+9-12-6с=
=1-12с
137+(193+358)=137+551=688
А) 2x - 5x + 10 = -3x - 6
-3x + 10 = -3x - 6
10 = -6
б) -3x + x - 5 = -2x - 8
-2x -5 = -2x -8
-5 = -8
в) x = 1 - 6
x = -5
г)-2 (x - 4) = 5 (1 - 3x)
-2x + 8 = 5 - 15x
-2x + 15x = 5 - 8
13 = -3
д)6 (1 - x) + 10 (2x - 4) = 3 (x + 3)
6 - 6 x + 20x - 40 = 3x + 9
-34 + 14x = 3x + 9
14x - 3x = 9 + 34
11x = 43
x = 43/11
е)9x^2 - 4 - (9x^2 - 2x + 16) = 28
9x^2 - 4 - 9x^2 + 24x - 16 = 28
-20 + 24x = 28
24x = 28 +200
24x = 48
x = 2