Can anyone point me in the right direction for this problem? I can't seem to approach it from the right angle: Let A, B, C be real numbers such that [tex]A>0[/tex], [tex]B>0[/tex], [tex]AC-B^2>0[/tex]. a. Prove that a number [tex]Q>0[/tex] exists such that [tex]Ax^2+2Bxy+Cy^2 \geq Q(x^2+y^2)[/tex] b. Find the largest possible Q. I don't need answers (or rather, I do, but, you know what I mean; my main concern is figuring out how to approach this without my head exploding. Thanks in advance.