Решить уравнение: 1) 14 - (2 + 3х - х2) = х2 + 4x -9,
2) 15 - (2 x2 – 4x) - (7x - 2 x ) = 0.
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1) 14 - (2 + 3х - х2) = х2 + 4x -9

14 - (2+3x - 2x) = 2x + 4x - 9

14 - (2 + x) = 6x - 9

14 - 2 - x = 6x - 9

12 - x = 6x-9

-x - 6x = -9 - 12

-7x = - 21

x=3

2)15 - (2 x2 – 4x) - (7x - 2 x ) = 0

15 - (4x - 4x) - 5x = 0

15 - 0 - 5x = 0

15 - 5x = 0

-5x = - 15

X = 3