c) → introduc intregii in fractie :
1 intreg si 1 / 5 = ( 1 x 5 + 1 ) / 5 = 6 / 5
7 intregi si 1 / 5 = ( 7 x 5 + 1 ) / 5 = 36 / 5
( - 3 / 4 + 1 / 8 ) × ( - 6 / 5 ) - ( - 5 / 24 ) × ( - 36 / 5 ) = - 3 / 4
= ( - 6 / 8 + 1 / 8 ) × ( - 6 / 5 ) - 3 / 2 = ( 36 / 24 ) = ( 36 : 12 ) / ( 24 : 12 ) = 3 / 2 ; 5 / 5 =1
= ( - 5 / 8 ) × ( - 6 / 5 ) - 3 / 2 =
= 6 / 8 - 3 / 2 =; 6 / 8 = ( 6 : 2 ) / ( 8 : 2 ) = 3 / 4
= 3 / 4 - 6 / 4 = → am amplificat fractia 3 / 2 cu 2 = 6 / 4
= - 3 / 4
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d)
( - 5 / 12 + 4 / 9 ) × ( - 9 / 2 ) - ( - 1 / 18 - 1 / 6 ) × ( + 27 / 8 ) = 5 / 8
→ cmmmc al numitorilor 12 si 9 este 36; amplific fractia 5 / 12 cu 3; iar fractia 4 / 9 cu 4
= ( - 15 + 16 ) / 36 × ( - 9 / 2 ) - ( - 1 / 18 - 3 / 18 ) × 27 / 8 =
= - 9 / 72 - ( - 4 / 18 ) × 27 / 8 =
= - 1 / 8 + ( 4 / 8 ) × ( 27 / 18 ) =
= - 1 / 8 + ( 1 / 2 ) × 3 / 2 =
= - 1 / 8 + 3 / 4 =
= - 1 / 8 + 6 / 8 =
= 5 / 8