Subtract the first equation from the second: $ 3a + b = 7 $. Subtract the second from the third: $ 5a + b = 11 $. Subtract these two results: $ 2a = 4 \Rightarrow a = 2 $. Substitute back: $ 3(2) + b = 7 \Rightarrow b = 1 $. Then $ 2 + 1 + c = 4 \Rightarrow c = 1 $. Thus, $ p(x) = 2x^2 + x + 1 $. - Nelissen Grade advocaten