I need help on this

Quadratic formula....

roots   -5.333  and  4.166     squared and added together = 45.79

Sorry but that was wrong

The sum of the roots = -b / a =  -21/18  =  -7/6

The product of the roots = c / a = -400/18 = -200/9

Let the roots be  p, q

p + q =   -7/6    

pq = -200/9    ⇒   2pq = -400/9

(p + q)^2 =   49/36

p^2 + 2pq + q^2 = 49/36

p^2 +  (-400/9) + q^2  = 49/36

p^2 + q^2 =  49/36 + 400/9

p^2 + q^2 =  [ 49 + 1600] / 36  = 1649 / 36   ≈   45.8....just as EP found !!!!