The relationship between two roots of a quadratic equation with one variable (Vieta theorem) ax 2+bx+c = 0, and the root of (a≠0) is x 1, x 2,

Then x 1+x2=-b/a, x1* x2 = c/a.

The meaning of the question is x 1= 1.2, x2= 1.5, and a= 1.

Then x1+x2 =-b/a =1.2+1.5 = 2.7, which means b=-2.7a=-2.7.

X1* x2 = c/a =1.2 *1.5 =1.8, which means c= 1.8a= 1.8.

So the equation is x 2+2.7x+ 1.8 = 0.