Question

pt a=50,calculati ax(a+2)-ax(a-2)

Answer 1

a×(a+2)-a×(a-2)=
50×(50+2)-50×(50-2)=
50×52-50×48=
2600-50×48=
2600-2400=200

Answer 2

$a=50\\a*(a+2)-a*(a-2)=\\=50*(50+2)-50*(50-2)=\\=50*52-50*48=\\=50*(52-48)=\\=50*4=200\\Gata!$