... 3 5 2 Bài a x x 10trang 8 SG x K − + − ÷ 3 2 2 1 3 5 10 15 2 2 x x x x x = − − + + − 3 2 1 23 6 15 2 2 x x x = − + − 32 23 322 23 33 22 yxyyxx yxyxyyxyxx −+−= −++−− =−+− ))(2(, 22 yxyxyxb ... 6 33 10 55 6 14 9 21x x x x x x= + − − − − − − 76=− Bài 12 trang 8 SGK x Giá trị của 0x = 15x = − 15x = 0,15x = - 15 0 -3 0 -1 5,15 ))(4( )3) (5( 22 xxxxx −+++− Gi¸ trÞ cña biÓu thøc 15 4415 53 232 23 ... biến: ( ) ( ) ( ) / 5 2 3 2 3 7a x x x x x − + − − + + 2 2 2 3 10 15 2 6 7x x x x x x = + − − − + + + 8 =− ( ) ( ) ( ) ( ) / 3 5 2 11 2 3 3 7b x x x x− + − + + ( ) ( ) 2 2 6 33 10 55 6 14 9 21x x...