The statement that says that a system constructed by a linear and a quadratic equation, has infinitely solutions is never true.
This situations can be explained more easy by the graphic solution of the system of equations. As we know, a cuadratic equation represents a parabola and the linear equation a line, so the solution of the system can be understood as the interseption od the parabola and the line.
In the attached figure above we expouse the three different cases could hapend. In the first case, we have two interceptions, so 2 solutions. For the second case, we have 1 interseption, which represents one solution. In the third case the line doesnt touch the parabola in any point thus we get no solution.
Therefore in none of the cases explained we found infinite solutions, this situacion can never happens.
In the example the second equation doesnot represents a quadratic equation. A quadratic equation has the form of:
Y = aX^2 + BX + C
Thus the given system cannot be understood as a the example of the kind.