If a and b are roots of the quadratic equation 3x^2-6x+2=0.
(i) Find a+b
(ii) Find ab
Anyone can help?
CaptainBlack's method is perfectly acceptable, but there is a general theorem for quadratics you can use to tackle this. (You can actually get theorems for this for higher order polynomials, but I forget the name of the method.)
If you have two roots of a quadratic equation , , then
and
(You can easily get this result by noting that
and doing the relevant sum or product of .)
In your particular case, we have a = 3, b = -6, and c = 2. Thus
and
just as CaptainBlack derived.
-Dan