rewrite a linear equation and a quadratic equation can intersect at most twice, so they cannot have an infinite number of solutions. but like a 9th grader

A linear equation (like a straight line) and a quadratic equation (which looks like a curve, like a U shape) can cross each other at most two times. This means they can only have up to two points where they are equal. So, they can't have an infinite number of solutions or points where they meet.