Question

Х^2-11х-42=0
-2х^2-5х-2=0
Х^4-13х^2+36=0
Решите уравнение

Answer 1

1)Д=121-4*-42=121+168=289
х=11+17/2=28/2=14
х=11-17/2=-6/2=-3
2)2х²+5х+2=0
Д=25-16=9
х=-5+3/4=-1/2
х=-5-3/4=-8/4=-2
3)пусть х²=t
t²-13t+36=0
D=168-144=25
t=13+5/2=9
t=13-5/2=8/2=4
=>x²1=+-3,x²2=+-2