Question

-х^2+5х+6=9
решите плиз

Answer 1

-х²+5х+6-9=0
-х²+5х-3=0
х²-5х+3=0

D=b²-4ac
D=25-12=13
√D=√13

x1=(5-√13)/2
x2=(5+√13/2)