Help with alpha beta roots question PLEASE? :) (1 Viewer)

[curiouscat98]

Hello all, I was doing some homework the teacher gave us for the weekend and got stuck on the last one:

Given the roots of a quadratic function are alpha=3+sqrt5 and beta=3-sqrt5, write an equation in the form ax^2+bx+c=0.

So far I've found alpha*beta equals 4 and alpha+beta equals 6. Not sure what to do next... any help would be greatly appreciated.

Thanks BOSers!
-CC.

 

[Librah]

x^2-(a+b)x+ab. Where a,b are the roots. Get that by expanding (x-a)(x-b)

 

[Librah]

So answer is x^2-6x+4

 

[curiouscat98]

x^2-(a+b)x+ab. Where a,b are the roots. Get that by expanding (x-a)(x-b)

That's actually so easy haha thanks so much! Can't believe I didn't realise to begin with lol.