#1**+1 **

Quadratic formula....

roots -5.333 and 4.166 squared and added together = 45.79

ElectricPavlov Feb 20, 2019

#4**+3 **

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 !!!!

CPhill Feb 20, 2019