Chapter 1.1, Problem 5QCE

The slope of the secant line through $P\left(2,4\right)$ and $Q\left(x,x^2\right)$ on the parabola $y=x^2$ is $m_{\sec }=x+2$ . It follows that the slope of the tangent line to this parabola at the point $P$ is $\text{\_\_\_\_\_\_\_}$ .