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30 dm²

43 m²

ôk

D

D?

d

chẳng phải tớ trl nó r?

Chiều cao hình bình hành: 15 : 3 = 5 (dm)

DIện tích tấm bìa: 15 \(\times\) 5 = 75 (dm²)

Đáp số: 75 dm²

\(\dfrac{48}{32}=\dfrac{12}{8}=\dfrac{6}{4}=\dfrac{3}{2}\)

a: 3/7=15/35

2/5=14/35

b: 3/8=9/24

7/12=14/24

c: 11/12=44/48

7/48=7/48

d: 1/2=6/12

2/3=8/12

3/4=9/12

e: 1/3=15/45

2/15=6/45

4/45=4/45

\(a.\dfrac{3}{7}=\dfrac{15}{35};\dfrac{2}{5}=\dfrac{14}{35}.\\ b.\dfrac{3}{8}=\dfrac{9}{24};\dfrac{7}{12}=\dfrac{14}{24}.\\ c.\dfrac{11}{12}=\dfrac{44}{48};\dfrac{7}{48}.\)

\(d.\dfrac{1}{2}=\dfrac{6}{12};\dfrac{2}{3}=\dfrac{8}{12};\dfrac{3}{4}=\dfrac{9}{12}.\\ e.\dfrac{1}{3}=\dfrac{15}{45};\dfrac{2}{15}=\dfrac{6}{45};\dfrac{4}{45}.\)

\(a,\dfrac{3}{7}và\dfrac{2}{5}\)

\(\dfrac{3}{7}=\dfrac{3\times5}{7\times5}=\dfrac{15}{35}\)\(;\dfrac{2}{5}=\dfrac{2\times7}{5\times7}=\dfrac{14}{35}\)

\(b,\dfrac{3}{8}và\dfrac{7}{12}\)

\(\dfrac{3}{8}=\dfrac{3\times3}{8\times3}=\dfrac{9}{24};\dfrac{7}{12}=\dfrac{7\times2}{12\times2}=\dfrac{14}{24}\)

\(c,\dfrac{11}{12}và\dfrac{7}{48}\)

\(\dfrac{11}{12}=\dfrac{11\times4}{12\times4}=\dfrac{44}{48};\dfrac{7}{48}\)

\(d,\dfrac{1}{2};\dfrac{2}{3}và\dfrac{3}{4}\)

\(\dfrac{1}{2}=\dfrac{1\times6}{2\times6}=\dfrac{6}{12};\dfrac{2}{3}=\dfrac{2\times4}{3\times4}=\dfrac{8}{12};\dfrac{3}{4}=\dfrac{3\times3}{4\times3}=\dfrac{9}{12}\)

\(e,\dfrac{1}{3};\dfrac{2}{15}và\dfrac{4}{45}\)

\(\dfrac{1}{3}=\dfrac{1\times15}{3\times15}=\dfrac{15}{45};\dfrac{2}{15}=\dfrac{2\times3}{15\times3}=\dfrac{6}{45};\dfrac{4}{45}\)

\(=\dfrac{3}{11}\cdot\dfrac{7\cdot5}{7\cdot5}=\dfrac{3}{11}\)

3/11

3/11

3/4 ; 

3/4

\(\dfrac{3}{4}=\dfrac{12}{16}\)

Bài 1: 

a: \(x=\dfrac{3^2}{2}=\dfrac{9}{2}=4.5\left(cm\right)\)

\(y=\sqrt{3^2+4.5^2}=\dfrac{3\sqrt{13}}{2}\left(cm\right)\)