Question

correct the statement( l -a^2) = l ^2 -81

Answer 1

it is correct as
${1}^{2} = 1 \\ and \: a \: can \: be \: 9 \\ {a}^{2} = {9}^{2} = 81 \\ (1 - {a}^{2} ) = {1}^{2} - 81$