# Expectation value of position of wavepacket

by Werbel22
Tags: expectation, position, wavepacket
 P: 675 You cannot square the integral. The way it is written is (in 1 dimension): $$\left = \int \psi(x)^{\dagger}x^2\psi(x) dx$$ It will be different in most cases from ^2. For example, $$\int x^2 dx = \tfrac13 x^3 \neq \left(\int x dx\right)^2 = \tfrac14 x^4$$ So you are unable to take the square outside of the integral.