[问答题]
Show that for an isotro6b7:) nnzz sdvpic solid,s f1xlopp.z3avzn 14 +r 7n2tfj*4azv $\beta$ = 3$\alpha$ if the amount of expansion is small. $\beta$ and $\alpha$ are the coefficients of volume and linear expansion, respectively. [Hint: Consider a cubical solid, and neglect very small quantities. See also Problem 18 and Fig. 13–30.]
