Răspuns
29 / 210 ; 77 / 36
Explicație pas cu pas:
a ) ( 1 / 21 + 1 / 14 ) - ( 1 / 35 - 1 / 42 ) + ( 1 / 14 - 1 / 21 ) =
= ( 2 + 3 / 42 ) - ( 6 - 5 / 210 ) + ( 3 - 2 / 42 )
= 5 / 42 - 1 / 210 + 1 / 42
= ( 25 - 1 + 5 ) / 210
= ( 24 + 5 ) / 210
= 29 / 210
b ) ( 4 1 / 6 - 1 1 / 9 ) - ( 11 / 8 - 7 / 24 ) + ( 1 / 10 + 1 / 15 ) =
= ( 25 / 6 - 10 / 9 ) - ( 11 / 8 - 7 / 24 ) + ( 1 / 10 + 1 / 15 )
= ( 75 - 20 ) / 18 - ( 33 - 7 ) / 24 + ( 3 + 2 ) / 30
= 55 / 18 - 26 / 24 + 5 / 30
= 55 / 19 - 13 / 12 + 1 / 6
= ( 110 - 39 + 6 ) / 36
= ( 71 + 6 ) / 36
= 77 / 36
