y=ax²+bx+c
1=a+b+c
2=4a+2b+c 1=3a+b
6=9a+3b+c 4=5a+b 3=2a a=3/2
b=1-3*3/2=1-9/2=-7/2
c=1-3/2-(-7/2)=1-3/2+7/2=3
y=3x²/2-7x/2+3