Đáp án + Giải thích các bước giải :
= 7/11 x ( 11/9+8/19 ) + 4/11 = 4/13 x ( 5/11 + 6/11 -1 )
= 7/11 x 1 + 4/11 = 4/13 x 0
= 7/11 + 4/11 = 0
= 1
= 4/19 x ( 6 /11 +5/11+2 ) = ( 3/11+17/11-13/11)x(7/19+3/19-3/19)
= 4/19 x 3 = 3/11x7/19
= 12/19
= 21/209
= (6/7+9/7-6/7)x(8/13+6/13-4/13) = 5/9x (7/13+9/13-3/13)
= 9/7x10/13 = 5/9 x 1
= 90/91 = 5/9
= 5/12x(6/11+5/11)+7/12 = 7/19x(8/11+3/11)+12/19
= 5/12x1+7/12 = 7/19x 1 +12/19
= 5/12 +7/12 = 7/19+12/19
=1
= 1
= 5/11 x (18/29 -8/29 +19 / 29 )
= 5/11x 1
= 5/11
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