2(2x-13)²-6(2x-13)+4=0

(2x-13)²-3(2x-13)+2=0  |:2

2x - 13 = t

t²-3t+2=0  

D = 9 - 8 = 1  дискриминант = 1 при замене

t12 = ( 3 +- 1)/2 = 1    2

1. 2x - 13 = 1

2x = 14

x = 7

2. 2x - 13 = 2

2x = 15

x = 7.5

ответ х = {7, 7.5}  D = 1

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