Question

(9х –3 у) · (9х +3 у)

Answer 1

(9х-3у)(9х+3у)=81х²-9у²

Answer 2

(9х –3у) · (9х +3у)= 81$x^{2}$+27xy-27xy-9$y^{2}$=81$x^{2}$-9$y^{2}$