3x(2/13)+4x(3/7)+5x(4/13)+6x(5/7) 详细过程 要简便
= 6/13 + 12 /7 + 20/13 + 30/7
= (6/13 + 20/13) +( 30 /7 + 12/7 )
= 26 13 + 42 /7
= 2 + 6
= 8
3x(2/13)+4x(3/7)+5x(4/13)+6x(5/7) 详细过程 要简便
= 6/13 + 12 /7 + 20/13 + 30/7
= (6/13 + 20/13) +( 30 /7 + 12/7 )
= 26 13 + 42 /7
= 2 + 6
= 8