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Determination of quadratic function;

On the right side of the equal sign in the general form of quadratic function is the quadratic trinomial about the independent variable x;

When b=0 and c=0, y=ax2 is a special quadratic function;

To judge whether a function is a quadratic function, on the premise that the relational expression is an algebraic expression, if the relational expression can be written in the form of (a≠0) after simplification (removing brackets and merging similar items), then the function is a quadratic function, otherwise it is not.

Structural characteristics of general form of quadratic function;

① The relationship between functions is algebraic expression;

② The maximum number of independent variables is 2;

③ Quadratic coefficient is not equal to zero.