Factor Theorem- Maths

F(x)= 2xsquared+px+q. Given that f(-3)=0 and f(4)=21. How do I find p and q?

Well basically I think the simplest way to do this is to make yourself a couple of simultaneous equations so given that f(-3) = 0 and f(4) =21 you can make the following two equations: 0=18-3p+q which also equals: 18= 3p -q (1) and 21= 32+4p +q which also equals: -11 = 4p +q (2) If we add equations (1) and (2) together then we can eliminate the q from both equations giving us: 7p=7 so p=1 Then putting p=1 back into either equation (1) or (2) we find that q=-15
20 January 2011
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