if x₁ & x₂ are the roots of the quadratic equation ax² +bx+c=0
then x₁+x₂ = -b/a & x₁x₂ = c/a
to form the equation use this pattern
x² - (sum of roots)x + (product of roots) =0
ex: write a quadratic whose roots are 2 & -5
solution
x₁+x₂ = 2 + (-5) = -3 sum of roots
x₁x₂ = 2*-5 -10 product of roots
so the equation is x²+3x -10=0
note the change from negative to positive of the sum of roots sign
