Question 422181
r squared-10r=39
r^2-10r-39=0

a= 1  , b =-10   , c = -39    .

b^2-4ac=256

{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}


{{{x1=(10+sqrt(256))/(2)}}}
x1=13
...
{{{x2=(10-sqrt(256))/(2)}}}
x2=-3