Question

Determine as somas e as diferenças.Simplifique quando possivel.
a)5/18+7/18=
b)27/35+8/35=
c)19/30+11/12=
d)17/24+101/144=
e)12/15-9/20=
f)9/25-11/100=
g)35/12-28/15=
h)31/18-17/30=

Answer 1

a) 5/18 + 7/18 = 12/18 = 6/9
b) 27/35 + 8/35 = 35/35 = 1
c) 19/30 + 11/12 = 38/60 + 55/60 = 93/60 = 31/20
d) 17/24 + 101/144 = 102/144 + 101/144 = 203/144
e) 12/15 - 9/20 = 48/60 - 27/60 = 21/60 = 7/20
f) 9/25 - 11/100 = 36/100 - 11/100 = 25/100 = 1/4
g) 35/12 - 28/15 = 175/60 - 112/60 = 63/60 = 21/20
h) 31/18 - 17/30 = 155/90 - 51/90 = 104/90 = 52/45

Answer 2

Quando temos soma / subtração de frações obedecemos às seguintes regras:
- Se as frações tem mesmo denominador, conservamos o denominador e somamos / subtraímos os numeradores.
- Se as frações tem denominadores diferentes, fazemos o MMC dos denominadores.


$a)~~ \dfrac{5}{18} + \dfrac{7}{18} \to~~ \dfrac{5+7}{18}\to~~ \dfrac{12}{18}\to ~~ \boxed{\dfrac{2}{3}} \\\\\\b)~~ \dfrac{27}{35} + \dfrac{8}{35} \to~~ \dfrac{27+8}{35}\to ~~ \dfrac{35}{35}\to ~~ \boxed{1} \\\\\\ c)~~ \dfrac{19}{30} + \dfrac{11}{12} \to~~mmc=60\to~~ \dfrac{38+55}{60}\to~~ \dfrac{93}{60}\to~~ \boxed{\dfrac{31}{20}} \\\\\\ d)~~ \dfrac{17}{24} + \dfrac{101}{144} \to~~mmc=144\to~~ \dfrac{102+101}{144} \to~~ \boxed{\dfrac{203}{144}}$



$e)~~ \dfrac{12}{15} - \dfrac{9}{20} \to~~mmc=60\to~~ \dfrac{48-27}{60}\to~~ \dfrac{21}{60}\to ~~ \boxed{\dfrac{7}{20}} \\\\\\f)~~ \dfrac{9}{25} - \dfrac{11}{100} \to~~mmc=100\to~~ \dfrac{36-11}{100}\to ~~ \dfrac{25}{100}\to ~~ \boxed{ \frac{1}{4} } \\\\\\ g)~~ \dfrac{35}{12} - \dfrac{28}{15} \to~~mmc=60\to~~ \dfrac{175-112}{60}\to~~ \dfrac{63}{60}\to~~ \boxed{\dfrac{21}{20}}$



$h)~~ \dfrac{31}{18} - \dfrac{17}{30} \to~~mmc=90\to~~ \dfrac{155-51}{90} \to~~ \dfrac{104}{90}\to~~ \boxed{\dfrac{52}{45}}$