Bµi 32 (sgk-trang 50) Bµi 32 (sgk-trang 50) 6)x(x 6 6)x(x x6x 6x 1 x 1 6x 1 5x 1 . 2x 1 1x 1 1x 1 x 1 6)5)(x(x 1 5)4)(x(x 1 4)3)(x(x 1 3)2)(x(x 1 2)1)(x(x 1 1)x(x 1 + = + −+ = = + −= + − + + ++ + − + + + −= = ++ + ++ + ++ + ++ + ++ + + TiÕt 32 TiÕt 32 : : phÐp nh©n c¸c ph©n thøc phÐp nh©n c¸c ph©n thøc 1) Quy t¾c : (sgk) ?2: Lµm tÝnh nh©n : 3 2x 13)3(x 13)(x 5 2x ) 2 3x( 2 13)(x 13x 2 3x 5 2x 2 13)(x −− = = − −− = − − −           ?3: thùc hiÖn phÐp tÝnh ?3: thùc hiÖn phÐp tÝnh : : 3)2(x 2 1)(x 3 3)1).2(x(x 3 1).(x 2 3)(x 3 3)2(x 3 1)(x . x1 96x 2 x +− − = +−− −+ = + − − ++ ?4:tÝnh nhanh ?4:tÝnh nhanh : : 32 1533227 27153 153 27 . 32 . 27 4 153 3524 2435 35 24 2 35 + = ++++− +−++ = = ++ +− + +− ++ x x )xx).(x).(x(x )x).x.(xxx( xx xx x x xx xx Bµi 40(sgk-trang53) Bµi 40(sgk-trang53) c¸ch 1:Sö dông tÝnh chÊt ph©n phèi :