Question

x2 -11x+18=0 x2 -4x-4=0 2x2-10x=0

Answer 1

x^2 - 11x + 18 = 0

D = b^2 - 4ac = (-11)^2 - 4*1*18 = 121-72 = 49

VD = V49 = 7

x1 = (11+7)/2 = 18/2 = 9

x2 = (11-7)/2 = 4/2 = 2

 

 

x^2 - 4x -4 = 0

D = b^2-4ac = 4^2-4*1*(-4) = 16+16 = 32

VD = V32 = V(16*2) = 4V2

 

             4+4V2           

x1 = ----------------- = 2+2V2

                2 

 

 

              4 - 4V2

 x2 = ----------------- = 2 - 2V2

                  2

 

2x^2 - 10x = 0

x (2x-10)=0

x = 0    i     2x-10=0

                  2x=10

                   x = 10:2

                    x = 5