It looks like you're asking to prove or solve an integral, but the expression is incomplete. It seems like you want to show something about the integral from 1 to 2 of a function involving $x$, but the function is not fully provided. Could you clarify the exact function you are working with?

For example, do you want to show:

• $\int_1^2 x \, dx$
• $\int_1^2 x^n \, dx$
• or something else?

Once you provide the function, I can walk you through the steps of solving it!

Let me know how you'd like to proceed.