Deriving quadratic equations

1. DERIVING QUADRATIC EQUATIONS

2.

ax² + bx + c = 0 as x² + b/ax + c/a=0
We know that
x1 + x2 = - b/a
x1 ∙ x2 = c/a

3.

find a quadratic equation whose only roots is 5
x1=x2=5

4.

ax² +b/ax + c/a =0
x1 + x2=10
x1 ∙ x2 =25
The equation is x² +(-10x) + 25=0