4(K+1)^2-1怎么算得到(2K+1)(2K+3)?
问题描述:
4(K+1)^2-1怎么算得到(2K+1)(2K+3)?
答
4(K+1)^2-1
=(2k+2)^2-1
=(2k+2+1)(2k+2-1)
=(2k+3)(2k+1)