1. D = 64 - 4*(-5)*(-3) =64-60=4=2²; x = -6/5; x= -3/10;
2. D = 100 - 4*3*7 = 100 - 84 = 16 =4²; x = 7/3;
3. D =121 - 4*4*7 = 121- 112 = 9 = 3² x = 1; x= 7/8;
4. D = 16 - 4*(-2)*6 = 16+48 =64 = 8²; x = - 1/6; x = - 7/6;
5. D = 121 - 4*3*(-4)= 169 = 13²; x = -4; x= 1/3;
6. Виет теорема x = 3; x = 1;
7. D = 4 -4*3*(-5)= 64 = 8²; x= - 2/3; x = 2;
8. Виет теор x =-7; x = 1; 9. x = 5; x=2;