1) (t+n)(t-n) = t^2 - tn + tn - n^2 = t^2 - n^22) (x+y)(y-x) = xy - x^2 + y^2 - xy = y^2 - x^23) (n-2t)(n+2t) = n^2 + 2nt - 2nt - 4t^2 = n^2 - 4t^2
1) (t+n)(t-n) = t^2 - tn + tn - n^2 = t^2 - n^2
2) (x+y)(y-x) = xy - x^2 + y^2 - xy = y^2 - x^2
3) (n-2t)(n+2t) = n^2 + 2nt - 2nt - 4t^2 = n^2 - 4t^2