6. √21-4=-

7. √54-3=-

8. √30-=-

9. √56+=-

10. √28+3=-

11. √36+5=-

12. √14-5=

13. √28-3=

14. √2-=

15. √12+=

16. √48+2=

17. √21+4=

18. √-8+6=

19. √18+7=

20. √-8+9=

21. √-35+12=

22. √-56+15=

6.21-4 х=х^2

x^2+4x-21=0

D=16+84=100>0

x1 = (-4-10) / 2=-14/2=-7

x2 = (-4+10) / 2=6/2=3

7.54-3x=x^2

x^2+3x-54=0

D=9+216=225>0

x1 = (-3-15) / 2=-18/2=-9

x2 = (-3+15) / 2=12/2=6

8.30-x=x^2

x^2+x-30=0

D=1+120=121>0

x1 = (-1-11) / 2=-12/2=-6

x2 = (-1+11) / 2=10/2=5

9.56+x=x^2

x^2-x-56=0

D=1+224=225>0

x1 = (1-15) / 2=-14/2=-7

x2 = (1+15) / 2=16/2=8