Toán Lớp 6: Tính phân số
a,-7/12+11/8-12/24
b,-3/7+11/8-5/14
c,5/18×-7/27–7/13×13/18-11/24
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Toán Lớp 6: Tính phân số
a,-7/12+11/8-12/24
b,-3/7+11/8-5/14
c,5/18×-7/27–7/13×13/18-11/24
Giúp em với mn
Comments ( 2 )
a) $\dfrac{-7}{12}$ + $\dfrac{11}{8}$ + $\dfrac{12}{24}$
= $\dfrac{-7}{12}$ + $\dfrac{11}{8}$ + $\dfrac{6}{12}$
= ( $\dfrac{-7}{12}$ + $\dfrac{12}{24}$ )+ $\dfrac{11}{8}$
= $\dfrac{-1}{12}$ + $\dfrac{11}{8}$
= $\dfrac{-2}{12}$ + $\dfrac{33}{24}$
= $\dfrac{31}{24}$
b) $\dfrac{-3}{7}$ + $\dfrac{11}{8}$ – $\dfrac{5}{14}$
= $\dfrac{-6}{14}$ – $\dfrac{5}{14}$ + $\dfrac{11}{8}$
= $\dfrac{-11}{14}$ + $\dfrac{11}{8}$
= $\dfrac{-88}{112}$ + $\dfrac{154}{112}$
= $\dfrac{66}{112}$
= $\dfrac{1}{2}$
c) $\dfrac{5}{18}$ × ( $\dfrac{-7}{27}$ ) – $\dfrac{7}{13}$ × + $\dfrac{13}{18}$ – $\dfrac{11}{24}$
= $\dfrac{5}{18}$ × ( $\dfrac{-7}{27}$ ) – $\dfrac{7}{18}$ – $\dfrac{11}{24}$
= $\dfrac{-35 }{486}$ – $\dfrac{189}{486}$ – $\dfrac{11}{24}$
= $\dfrac{154}{486}$ – $\dfrac{11}{24}$
= $\dfrac{616}{1944}$ – $\dfrac{891}{1944}$
= $\dfrac{275}{1944}$
a,-7/12+ 11/8- 12/24
= $\frac{-14+33-12}{24}$
= 7/24
b,-3/7+ 11/8- 5/14
= $\frac{-24+77-20}{56}$
= 33/56
c,5/18× -7/27- 7/13× 13/18- 11/24
= 35/486- 7/18- 11/24
= $\frac{140-756-891}{1944}$
= -1507/1944
Chúc bạn học tốt 🙂
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