Algebra 1: Common Core (15th Edition)

$7^{2}$ $\times$ $7^{6}$ = 7$\times$7$\times$7$\times$7$\times$7$\times$7$\times$7$\times$7 = $7^{8}$ = $7^{2+6}$
The expression uses the exponents law for adding the exponents when the base is the same. $7^{2}$ $\times$ $7^{6}$ = $7^{2+6}$ = $7^{8}$