1) (x+y)(x-y) = x^2 - xy + xy - y^2 = x^2 - y^22) (k+t)(k-t) = k^2 - kt + kt - t^2 = k^2 - t^23) (n+1)(n-1) = n^2 - n + n - 1 = n^2 - 14) (2a-3b)(3b+2a) = 6ab - 9b^2 + 6ab + 4a^2 = 10ab + 4a^2 - 9b^25) (5a-b)(5a+b) = 25a^2 - 5ab + 5ab - b^2 = 25a^2 - b^26) (7m+3n)(7m-3n) = 49m^2 - 21mn + 21mn - 9n^2 = 49m^2 - 9n^2
1) (x+y)(x-y) = x^2 - xy + xy - y^2 = x^2 - y^2
2) (k+t)(k-t) = k^2 - kt + kt - t^2 = k^2 - t^2
3) (n+1)(n-1) = n^2 - n + n - 1 = n^2 - 1
4) (2a-3b)(3b+2a) = 6ab - 9b^2 + 6ab + 4a^2 = 10ab + 4a^2 - 9b^2
5) (5a-b)(5a+b) = 25a^2 - 5ab + 5ab - b^2 = 25a^2 - b^2
6) (7m+3n)(7m-3n) = 49m^2 - 21mn + 21mn - 9n^2 = 49m^2 - 9n^2