(1/3)k(4k^2-1)+(2k+1)^2为什么=(1/3)(k+1)[4(k+1)^2-1]

问题描述:

(1/3)k(4k^2-1)+(2k+1)^2为什么=(1/3)(k+1)[4(k+1)^2-1]
要什么公式?求详解

(1/3)k(4k^2-1)+(2k+1)^2=(1/3)k(2k-1)(2k+1)+(2k+1)^2=(1/3)(2k+1)[ k(2k-1) +3(2k+1) ]=(1/3)(2k+1)(2k^2+5k+3)=(1/3)(2k+1)(2k+3)(k+1)=(1/3)(k+1)( 4k^2+8k+3 )=(1/3)(k+1)( 4(k+1)^2 -1)���һ���Ⱥ�û�п���Ŷ4(k+1)^2 -1=4k^2+8k +4 -1=4k^2+8k +3