\(\frac{12}{15}.\frac{30}{24}-1=1-1=0\)

\(\frac{12}{15}\)x \(\frac{30}{24}\)- 1 

= 1 - 1

= 0

15/30+2/5=1/2+2/5=9/10

15/30 + 2/5 = 1/2 +2/5 = 9/10

c1

a,3/15 = 3:3/15:3  = 15 

33/44 = 33:11/44:11 = 34 

2/8 = 2:2/8:2 = 1/4 

b,9/12 =9:3/12:3  = 34 

24/36 =24:12/36:12 = 23 

3/8 = 3:1/8:1 = 3/8 

c2

a) =12x(4+6)/24

= 12x10/24

=120/24

=5

b,16x8-16x2/12x4

=16x(8-2)/48

=16x6/48

=2

c3

5/8=45/72

20/15=4/3=96/72

24/32=3/4=54/72

15/18=5/6=60/72

77/99=7/9=56/72

c4

2/3=2/3

12/15=4/5

24/18=4/3

16/48=1/3

75/100=3/4

30/45=2/3

12/36=1/3

20/15=4/3

các phân số lớn hơn 1 luôn có mẫu số bé hơn tử số 

vậy các số lớn hơn 1 là  24/18,20/15

k mk nha thank mọi ng'

a, \(\frac{3}{15}=\frac{1}{5}=\frac{4}{20}\);   \(\frac{33}{44}=\frac{3}{4}=\frac{15}{20}\);       \(\frac{2}{8}=\frac{1}{4}=\frac{5}{20}\)

b, \(\frac{9}{12}=\frac{3}{4}=\frac{18}{24}\);     \(\frac{24}{36}=\frac{2}{3}=\frac{16}{24}\);      \(\frac{3}{8}=\frac{9}{24}\)

Bài 2 :

a,\(\frac{12x4+12x6}{24}=\frac{12x\left(4+6\right)}{24}=\frac{1x10}{2}=\frac{10}{2}=\frac{5}{1}\)

b, \(\frac{16x8-16x2}{12}=\frac{16x\left(8-2\right)}{12}=\frac{8x6}{6}=\frac{8}{1}\)

\(\frac{15}{a}\cdot\frac{2}{3}\cdot\frac{3}{2}=\frac{5}{4}\)

       \(\frac{15}{a}\cdot\frac{2}{3}=\frac{5}{4}:\frac{3}{2}\)

       \(\frac{15}{a}\cdot\frac{2}{3}=\frac{5}{4}\cdot\frac{2}{3}\)

       \(\frac{15}{a}\cdot\frac{2}{3}=\frac{10}{12}\)

       \(\frac{15}{a}\cdot\frac{2}{3}=\frac{5}{6}\)

              \(\frac{15}{a}=\frac{5}{6}:\frac{2}{3}\)

              \(\frac{15}{a}=\frac{5}{6}\cdot\frac{3}{2}\)

              \(\frac{15}{a}=\frac{15}{12}\)

Ta có: \(\frac{15}{a}=\frac{15}{12}\) 

Mặt khác: 15 = 15 => a = 12

Vậy a tìm được bằng 12

a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)

\(=\left(\frac{18}{15}+\frac{12}{5}\right)+\frac{7}{15}\)

\(=6+\frac{7}{15}\)

\(=\frac{97}{15}\)

b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)

\(=\frac{17}{7}+\frac{11}{7}\)

\(=\frac{28}{7}=4\)

TL

a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)\(=\frac{97}{15}\)

b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)\(=4\)

nha bn

HT

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