Question

x^2-14-72=0 2x^2-11x-21=0

Answer 1

1) D=196-4(-72)=484; √484= 22
x1=14+22 : 2 =18
x2=14-22 : 2 = -4
2) D=121+4×2×21=289; √289=17
x1=11+17 : 4 = 7
x2=11-17 : 4 = -1,5