How would you do this one with the substitution method?

Equation

Find an equation with roots + and +

Example of what i mean:

has roots and

Find an equation with and

Substitution would be:

Let u =

hence =

Sub it into equation gives.

When multiplied out gives

Uh, i don't mean to sound patronising when i gave an example since i know a lot of you are muuuch better at maths then me . Just wanted to make sure my question was clear, thats all .

Thankyou very much