Question

Which two values of x are roots of the polynomial below?

x²-11x+13
A. x = 11+√-109/4
B. x = 3
C. x = 11-√69/2
D. x = 11-√-109/4
E. x = 11+√69/2
F.x=2.5

Answer 1

x² - 11x + 13

Δ = (-11)² - 4*1*13 = 121 - 52 = 69

therefore :

x1 = [-(-11) + √69]/2*1

<=> x1 = (11 + √69)/2

and

x2 = [-(-11) - √69]/2*1

<=> x2 = (11 - √69)/2

so the correct answers are : C & E