Hello there!
You have plenty of time to improve. Please don't give up hope
I'd suggest pinpointing what exactly it is that is causing you to perform at a level you aren't happy with. If you make mistakes often (mistakes are a really good form of learning by the way, especially in maths), what kind of mistakes are they? (e.g. calculation error, lack of understanding of a concept etc)
Once you have pinpointed areas for improvement, you could go through practising those sorts of concepts with a teacher (even if it's not your own one), a friend or on your own. There are some helpful videos on YouTube too like Eddie Woo's videos, and here on the forum too, like the VCE Methods Question thread.
As for the question you have asked, how far have you gotten in solving it? Are you aware of the different forms of equations (e.g. y = ax^2 + bx + c - polynomial form, or y = a(x-h)^2 + k - turning point form)?