Question

please solve

(7m+3n)²-(7m-3n)²​

Answer 1

formula :

${a}^{2} - {b}^{2} = (a + b)(a - b)$

given :

$(7m + 3n) {}^{2} - (7m - 3n) {}^{2}$

apply the formula

$(7m + 3n) {}^{2} - (7m - 3n) {}^{2} \\ \\ = (7m + 3n + 7m - 3n)(7m + 3n - (7m - 3n)) \\ \\ = (14m)(7m + 3n - 7m + 3n) \\ \\ = (14m)(6n) \\ \\ = 84mn$

84mn is the answer