Question

d) (-2/21) + (-3/7) + (+5/42) + (-9/14)=

e) (-7/11) + (-1/4) + (+1/2) + (-5/22)=

f) 2/7 + (-1/14) + (+5/6) + (-13/42)=

Answer 1

d) (-2/21) + (-3/7) + (+5/42) + (-9/14)=
= -2/21 - 3/7 + 5/42 - 9/14 =
= -2×2/42 - 3×6/42 + 5/42 - 9×3/42 =
= -4/42 - 18/42 + 5/42 - 27/42 =
= (-4-18+5-27)/42 =
= -44/42 =
= - 22/21

e) (-7/11) + (-1/4) + (+1/2) + (-5/22)=
= -7/11 - 1/4 + 1/2 - 5/22 =
= -7×4/44 - 1×11/44 + 1×22/44 - 5×2/44 =
= -28/44 - 11/44 + 22/44 - 10/44 =
= (-28-11+22-10)/44 =
= -27/44

f) 2/7 + (-1/14) + (+5/6) + (-13/42)=
= 2/7 - 1/14 + 5/6 - 13/42 =
= 2×6/42 - 1×3/42 + 5×7/42 - 13/42 =
= 12/42 -3/42 + 35/42 - 13/42 =
= (12-3+35-13)/42 =
= 31/42