the function y = ax^2 + bx + c

a<0 has is maximum equal to c - b^2/(4a)

a>0 has is minimum equal to c - b^2/(4a)

f(x)=3.2x^2+6.2x-4.3

a = 3.2, b = 6.2, c = -4.3

a>0 follows the function has minimum

f min = - 4.3 - 6.2^2/(4*3.2)

f min = - 7.3

click here to see the graph of the function