460 Решите уравнение: a) (x+2)+x-9; 6) x+(7+ x) = 11; c)+2x-540;

Решение:

1. a) (x + 2) + x = 9 x + 2 + x = 9 2x + 2 = 9 2x = 9 - 2 2x = 7 x = 7 / 2 x = 3.5
2. б) x + (7 + x) = 11 x + 7 + x = 11 2x + 7 = 11 2x = 11 - 7 2x = 4 x = 4 / 2 x = 2
3. в) x + 2x - 5 = 40 3x - 5 = 40 3x = 40 + 5 3x = 45 x = 45 / 3 x = 15
4. г) x + (x + 4) + x = 16 x + x + 4 + x = 16 3x + 4 = 16 3x = 16 - 4 3x = 12 x = 12 / 3 x = 4
5. д) (х + 5) + (x + 5) = 21 x + 5 + x + 5 = 21 2x + 10 = 21 2x = 21 - 10 2x = 11 x = 11 / 2 x = 5.5
6. e) 2(x - 8) = 20 2x - 16 = 20 2x = 20 + 16 2x = 36 x = 36 / 2 x = 18

Ответ: а) x = 3.5; б) x = 2; в) x = 15; г) x = 4; д) x = 5.5; e) x = 18.