Решите уравнение. ,,,,,,,,

Question

Решите уравнение.
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Answer 1

3x^2 + 3x - 7x - 7 = x^2 + 6x+  9 - 18
3x^2 - 4x - 7 = x^2 + 6x - 9 
3x^2 - 4x - 7 - x^2 - 6x + 9 = 0
2x^2 - 10x + 2 = 0  /:2
x^2 - 5x + 1 = 0 
D=  25 - 4 = 21
x1 = ( 5 + √21)/2;
x2 = ( 5 - √21)/2