1, the expression of linear function is y=kx+b, and b is a constant term; The expression of quadratic function is expressed as y=ax? +bx+c, c is a constant term.

2. For linear and quadratic functions, when x=0, the value of y is the value of b or the value of c. ..

3. When a linear function passes through the origin, or the vertex of a quadratic function is at the origin, the constant term is 0.