(х²-5х+6)-5(х²-5х+6)+6=0
х²-5х+6-5х²+25х-30+6=0
-4х²+20х-18=0 |:(-2)
2х²-10х+9=0
D=100-4×2×9=100-72=28
х1 = (10+√28)/(2×2) = (10+√(4×7))/4 = (10+2√7)/4 = (5+√7)/2
х2 = (10-√28)/(2×2) = (10-√(4×7))/4 = (10-2√7)/4 = (5-√7)/2
ответ: х1 = (5+√7)/2, х2 = (5-√7)/2
