Phép cộng phân số (tiếp theo)

Đề thiếu rồi bạn

ko phải đề thiếu đâu , đề thế mà

\(\dfrac{3}{5}+\dfrac{11}{15}=\dfrac{9}{15}+\dfrac{11}{15}=\dfrac{20}{15}\)

\(\dfrac{3}{4}+\dfrac{5}{6}=\dfrac{9}{12}+\dfrac{10}{12}=\dfrac{19}{12}\)

a.3/5+11/15=9/15+11/15=4/3

b).3/4+5/6=18/24+20/24=19/12

A=\(\dfrac{4}{3}\)

a) \(=\dfrac{3}{5}+\dfrac{11}{15}=\dfrac{9}{15}+\dfrac{11}{15}=\dfrac{20}{15}=\dfrac{4}{3}\)

b) 34+56=90

a.\(\dfrac{3}{5}+\dfrac{11}{15}=\dfrac{9}{15}+\dfrac{11}{15}=\dfrac{20}{15}=\dfrac{4}{3}\)

b. 34+56=90

\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26+12}{81}=\dfrac{38}{81}\)

\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5+56}{64}=\dfrac{61}{64}\)

\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26}{81}+\dfrac{4\times3}{27\times3}=\dfrac{26}{81}+\dfrac{12}{81}=\dfrac{38}{81}\)

\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5}{64}+\dfrac{7\times8}{8\times8}=\dfrac{5}{64}+\dfrac{56}{64}=\dfrac{61}{64}\)

=83/9+9=83/9+81/9=164/9

 \(\dfrac{164}{9}\)

164/9

\(\dfrac{2}{5}+\dfrac{4}{7}=\dfrac{14}{35}+\dfrac{20}{35}=\dfrac{34}{35}\)

\(\dfrac{3}{5}+\dfrac{4}{3}=\dfrac{9}{15}+\dfrac{20}{15}=\dfrac{29}{15}\)

\(\dfrac{14}{35}+\dfrac{20}{35}=\dfrac{34}{35}\)

\(\dfrac{9}{15}+\dfrac{20}{15}=\dfrac{29}{15}\)

a: 5/6+1/2=5/6+3/6=8/6=4/3

b: 7/8+1/4=7/8+2/8=9/8

c: 5/9+3/7=35/63+27/63=62/63

\(a,\dfrac{5}{6}+\dfrac{1}{2}=\dfrac{4}{3}\\ b,\dfrac{7}{8}+\dfrac{1}{4}=\dfrac{9}{8}\\ c,\dfrac{5}{9}+\dfrac{3}{7}=\dfrac{62}{63}\)

\(a,\dfrac{5}{6}+\dfrac{1\times3}{2\times3}=\dfrac{5}{6}+\dfrac{3}{6}=\dfrac{8}{6}=\dfrac{4}{3}\\ b,\dfrac{7}{8}+\dfrac{1\times2}{4\times2}=\dfrac{7}{8}+\dfrac{2}{8}=\dfrac{9}{8}\\ c,\dfrac{5\times7}{9\times7}+\dfrac{3\times9}{7\times9}=\dfrac{35}{63}+\dfrac{27}{63}=\dfrac{62}{63}\)

Bài 2: 

a: 3/12+1/4=1/4+1/4=2/4=1/2

b: 4/25+3/5=4/25+15/25=19/25

c: 26/81+4/27=26/81+12/81=38/81

d: 5/64+7/8=5/64+56/64=61/64

a: S

b: Đ

c: S

d: Đ

e: Đ

- Câu sai: 1, 3
- Câu đúng: 2, 4, 5

a: =(3/7+4/7)+(4/9+5/9)=1+1=2

b: =(1/5+4/5)+(4/11+7/11)=1+1=2

c: =(1+4)/15+(5+7)/18=1/3+2/3=1

d: =(1/8+3/8)+(1/12+5/12)=1/2+1/2=1

\(a)(3/7+4/7)+(4/9+5/9)=1+1=2\)

\(b)(1/5+4/5)+(4/11+7/11)=1+1=2\)

\(c)(1/15+4/15)+(5/18+7/18)=1/3+2/3=1\)

\(d)(1/8+3/8)+(1/12+5/12)=1/2+1/2=1\)

(3/7+4/7)+(4/9+5/9)=1+1=2

(1/5+4/5)+(4/11+7/11)=1+1=2

(1+4)/15+(5+7)/18=1/3+2/3=1

(1/8+3/8)+(1/12+5/12)=1/2+1/2=1