25*(X+Y)的平方-16*(X-Y)的平方=多少?
问题描述:
25*(X+Y)的平方-16*(X-Y)的平方=多少?
答
25*(X+Y)的平方-16*(X-Y)的平方 =[5(X+Y)+4(X-Y)][5(X+Y)-4(X-Y)] =(5X+5Y+4X-4Y)(5X+5Y-4X+4Y) =(9X-Y)(X+9Y)
25*(X+Y)的平方-16*(X-Y)的平方=多少?
25*(X+Y)的平方-16*(X-Y)的平方 =[5(X+Y)+4(X-Y)][5(X+Y)-4(X-Y)] =(5X+5Y+4X-4Y)(5X+5Y-4X+4Y) =(9X-Y)(X+9Y)