f(x)=ax²+bx+c
A(1;14)⇒x=1;y=f(x)=14
f(x)=ax²+bx+c⇔14=a*1²+b*1+c⇔14=a+b+c
B(2;17)⇒x=2;y=17
f(x)=ax²+bx+c⇔17=4a+2b+c
C(1/2;41/4)⇒x=1/2;y=41/4
f(x)=ax²+bx+c⇔41/4=a/4+b/2+c⇔41=a+2b+c
14=a+b+c (1)
17=4a+2b+c (2)
41=a+2b+c (3)
17-41=3a⇔-24=3a⇒a=-8 ( am scazut ec.2 cu 3 )
41-14=b⇔b=27 ( am scazut ec. 3 cu 1 )
c=-5
f(x)=-8x²+27x-5
