题目计算:(1)(x−3y)(x+4y)(1)\left(x-3y\right)\left(x+4y\right)(1)(x−3y)(x+4y)；(2)(16m3−2m2)÷2m(2)(16m^{3}-2m^{2})\div 2m(2)(16m3−2m2)÷2m；(3)(3a+b)(3a−b)(3)\left(3a+b\right)\left(3a-b\right)(3)(3a+b)(3a−b)；(4)(5x−1)2(4)\left(5x-1\right)^{2}(4)(5x−1)2.知识点：提公因式法章节：数与式 / 因式分解
