根据2+4=6=2x3 2+4+6=12=3x4 2+4+6+8=20=4x5 2+4+6+8+10=30=5x6 计算 2a+4a+6a+.+100a的和根据2+4=6=2x3 2+4+6=12=3x4 2+4+6+8=20=4x5 2+4+6+8+10=30=5x6计算126a+128a+130a+132a.+300a的和
问题描述:
根据2+4=6=2x3 2+4+6=12=3x4 2+4+6+8=20=4x5 2+4+6+8+10=30=5x6 计算 2a+4a+6a+.+100a的和
根据2+4=6=2x3 2+4+6=12=3x4 2+4+6+8=20=4x5 2+4+6+8+10=30=5x6
计算126a+128a+130a+132a.+300a的和
答
n/2(n/2+1)a,即,50*51a