Question

7. 2х = - х2 -1.
8. 20х + 25х2 = - 4.
9. -1 - 4х2 = 0.

Answer 1

х2+2х+1=0
д=4-4×1×1=0 1к
х=-2/2=-1

25х2+20х+4=0
д=400-4×25×4=0
х=-20/50=-0,4

-4х2-1=0/-1
4х2+1=0
х2=-0,25
х=+-0,5