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A) 1/2 + 1/4 = 4/8 + 2/8= 6/8
B) 2/3 + 1/6 = 12/18 + 3/18 = 15/18
C) 7/12 + 1/2 = 14/24 + 12/24 = 26/24
D) 1/8 + 3/4 = 4/32 + 24/32 = 28/32
E) 2/3 + 1/12 = 24/36 + 3/36 = 27/36
G) 5/8 + 5/24 = 120/192 + 40/192 = 160 / 192
K a nha
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A) 3/4 + 1/5 = 15/20 + 4/20= 19/20
B) 1/36 + 5/12 = 12/432 + 180/432=192/864
C) 3/4 + 1/6 = 18/24 + 4/24 = 22/24
D) 1/8 + 7/10 = 10/80 + 56/80=66/160
E) 1/8 + 5/6= 6/48 + 40/48= 46/48
G) 2/3 + 2/7 = 14/21+6/24= 20/24
K nha
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A) 1/4 + 5/6=6/24+20/24=26/24
B) 2/9 + 1/9 = 3/9
C)1/6 + 3/8 = 8/48 + 18/48 = 26/48
(d) 3/10 + 5/8= 14/80 + 50/80= 64/160
(E) 7/12 + 1/8 = 56/96+12/96=68/192
(G) 3/20 + 7/2=6/24+20/24=26/24
K nha
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A) 1/3 + 1/6 + 1/18 = 6/18 + 3/18 = 9/18+ 1/8= 10/8
B) 1/20 + 1/4 + 2/5 = 4/80 + 20/80 = 24/80 + 2/5 = 120/400+160/400 = 280/400
C) 1/12 + 1/6 + 3/4 = 6/72 + 12/72 = 18/72
D) 1/4 + 2/25 + 3/100 = 33/100 + 3/100= 36/100
K nha
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a) 5/9 4/9=1
b) 2/3+1/3=1
c) 1/4 + 3/4=1
d) 9/11 + 2/11=1
e) 7/12 + 5/12=1
g) 2/5 + 3/5=1
Kết luận: Khi tử số và mẫu số bằng nhau khi rút gọn sẽ bằng 1. Vì vậy, nếu muốn làm phép tính hai phân số có mẫu số bằng nhau cộng với nhau bằng 1, đầu tiên, ta sẽ xác định mẫu số là bao nhiêu, sau đó lấy mẫu số trừ đi tử số đã cho sẽ ra tử số của phân số kia còn mẫu số vẫn sẽ giữ nguyên.
Chúc bạn thành công!!
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A) 3/7 + 4/9 + 4/7 + 5/9 = ( 4/9+5/9) + ( 3/7 + 4/7) = 1+ 1 = 2
B) 1/5 + 4/11 + 4/5 + 7/11 = ( 4/11 + 7/11) + ( 1/5 + 4/5) = 1+1=2
C) 1/15 + 4/15 + 5/18 + 7/18= ( 1/15+4/15) + (5/18+7/15)= 5/15 + 12/15 = 17/15
D) 1/8 + 1/12 + 3/8 + 5/12 = (1/8 + 3/8) + ( 1/12 + 1/12) = 4/8 + 2/12 = 64/96
K nha
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A\(\frac{1}{2}+\frac{1}{2}=\frac{2}{4}=\frac{1}{2}\)
B\(\frac{3}{8}+\frac{1}{8}=\frac{4}{8}=\frac{1}{2}\)
C\(\frac{7}{9}+\frac{5}{9}=\frac{12}{9}=\frac{4}{3}\)
D\(\frac{1}{6}+\frac{2}{6}=\frac{3}{6}=\frac{1}{2}\)
E\(\frac{3}{8}+\frac{7}{8}=\frac{10}{8}=\frac{5}{4}\)
G\(\frac{2}{5}+\frac{3}{5}=\frac{5}{5}=1\)
*cho mik sửa câu a:
\(\frac{1}{2}+\frac{1}{2}=\frac{2}{2}=1\)
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1.
\(\frac{5}{3}-\frac{1}{4}+\frac{1}{3}-\frac{3}{4}\)
\(=\left(\frac{5}{3}+\frac{1}{3}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)\)
\(=2-1=1\)
\(\frac{2}{7}\cdot\frac{1}{5}+\frac{2}{7}\cdot\frac{4}{5}=\frac{2}{7}\cdot\left(\frac{1}{5}+\frac{4}{5}\right)=\frac{2}{7}\cdot1=\frac{2}{7}\)
#Louis
\(1.a)\frac{5}{3}-\frac{1}{4}+\frac{1}{3}-\frac{3}{4}\)
\(=\left(\frac{5}{3}+\frac{1}{3}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)\)
\(=2-1\)
\(=1\)
\(b)\frac{2}{7}\times\frac{1}{5}+\frac{2}{7}\times\frac{4}{5}\)
\(=\frac{2}{7}\times\left(\frac{1}{5}+\frac{4}{5}\right)\)
\(=\frac{2}{7}\times1\)
\(=\frac{2}{7}\)
\(2.a)\frac{5}{6}+\frac{7}{12}-\frac{2}{9}\)
\(=\frac{30}{36}+\frac{21}{36}-\frac{8}{36}\)
\(=\frac{43}{36}\)
\(b)\frac{4}{9}\times\frac{5}{8}+\frac{1}{6}\)
\(=\frac{5}{18}+\frac{1}{6}=\frac{5}{18}+\frac{3}{18}\)
\(=\frac{8}{18}=\frac{4}{9}\)
\(c)2:\frac{3}{11}-\frac{13}{12}\)
\(=2\times\frac{11}{3}-\frac{13}{12}\)
\(=\frac{22}{3}-\frac{13}{12}\)
\(=\frac{25}{4}\)
A\(\frac{1}{4}+\frac{2}{3}=\frac{3}{12}+\frac{8}{12}=\frac{11}{12}\)
B\(\frac{2}{7}+\frac{2}{3}=\frac{6}{21}+\frac{14}{21}=\frac{20}{21}\)
C\(\frac{2}{5}+\frac{1}{4}=\frac{8}{20}+\frac{5}{20}=\frac{13}{20}\)
D\(\frac{1}{2}+\frac{1}{3}=\frac{3}{6}+\frac{2}{6}=\frac{5}{6}\)
E\(\frac{1}{3}+\frac{3}{5}=\frac{5}{15}+\frac{9}{15}=\frac{14}{15}\)
G\(\frac{4}{5}+\frac{1}{2}=\frac{8}{10}+\frac{5}{10}=\frac{13}{10}\)
a, 1/4 + 2/3 = 2/12 + 8/12 = 10/12 = 5/6
b, 2/7 +2/3 = 6/21 + 14/21 = 20/21
c, 2/5 + 1/4 = 8/20 + 5/20 = 13/20
d, 1/2 + 1/3 = 3/6 + 2/6 = 5/6
e, 1/3 + 3/5 = 5/15 + 9/15 =14/15
g, 4/5 + 1/2 = 8/10 + 5/10 = 13/10