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a/
\(\dfrac{4}{15}=1-\dfrac{11}{15}\)
\(\dfrac{5}{16}=1-\dfrac{11}{16}\)
\(\dfrac{11}{15}>\dfrac{11}{16}\Rightarrow1-\dfrac{11}{15}< 1-\dfrac{11}{16}\Rightarrow\dfrac{4}{15}< \dfrac{5}{16}\)
b/
\(\dfrac{2}{113}=\dfrac{4}{226}< \dfrac{4}{115}\)
c/ \(\dfrac{2}{7}=\dfrac{4}{14}< \dfrac{4}{9}\)
d/ \(\dfrac{2}{5}=\dfrac{4}{10}< \dfrac{4}{7}\)
a,\(\dfrac{4}{15}< \dfrac{5}{16}\)
b,\(\dfrac{2}{113}< \dfrac{4}{115}\)
c,\(\dfrac{2}{7}< \dfrac{4}{9}\)
d,\(\dfrac{4}{7}>\dfrac{2}{5}\)
7.a)A
b)C
1.
a)
a.6,25m
b.0,25km2
c.4,036 tấn
b) x=27
2.
\(a,x+\dfrac{3}{7}=\dfrac{8}{9}\\ \Rightarrow x=\dfrac{8}{9}-\dfrac{3}{7}\\ \Rightarrow x=\dfrac{29}{63}\)
\(b,\dfrac{4}{9}\times x=\dfrac{15}{27}\\ \Rightarrow x=\dfrac{15}{27}:\dfrac{4}{9}\\ \Rightarrow x=\dfrac{5}{4}\)
câu 3:
mua 45 quyển sách hết số tiền là: \(135000:15\times45=405000\)
câu 4:
nửa chu vi hcn là: \(90:2=45\left(m\right)\)
chiều dài là:\(45:\left(2+1\right)\times2=30\left(m\right)\)
chiều rộng là:\(45-30=15\left(m\right)\)
1a)\(\frac{5}{3}\)=\(\frac{5x4}{3x4}\)=\(\frac{20}{12}\); \(\frac{1}{4}\)=\(\frac{1x3}{4x3}\)=\(\frac{3}{12}\)
b)\(\frac{3}{8}\)=\(\frac{3x3}{8x3}\)=\(\frac{9}{24}\); \(\frac{7}{24}\)
c)\(\frac{1}{2}\)=\(\frac{1x15}{2x15}\)=\(\frac{15}{30}\); \(\frac{2}{3}\)=\(\frac{2x10}{3x10}\)=\(\frac{20}{30}\); \(\frac{3}{5}\)=\(\frac{3x6}{5x6}\)=\(\frac{18}{30}\)
2a)\(\frac{11}{8}\)>\(\frac{11}{9}\)
b)\(\frac{4}{9}\)<\(\frac{3}{5}\)
c)\(\frac{6}{5}\)>\(\frac{5}{6}\)
a; Cách một:
\(\dfrac{2}{9}\) = \(\dfrac{2\times2}{9\times2}\) = \(\dfrac{4}{18}\) < \(\dfrac{4}{10}\) Vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)
\(\dfrac{4}{9}\) = \(\dfrac{4\times3}{9\times3}\) = \(\dfrac{12}{27}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times2}{10\times2}\) = \(\dfrac{12}{20}\)
Vì \(\dfrac{12}{27}\) < \(\dfrac{12}{20}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{12}{20}\)
\(\dfrac{3}{8}\) = \(\dfrac{3\times4}{8\times4}\) = \(\dfrac{12}{24}\); \(\dfrac{4}{7}\) = \(\dfrac{4\times3}{7\times3}\) = \(\dfrac{12}{21}\)
Vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)
\(\dfrac{5}{9}\) = \(\dfrac{5\times7}{9\times7}\) = \(\dfrac{35}{63}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times5}{10\times5}\) = \(\dfrac{35}{50}\)
Vì \(\dfrac{35}{63}\) < \(\dfrac{35}{50}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)
Cách hai:
a; \(\dfrac{2}{9}\) = \(\dfrac{2\times10}{9\times10}\) = \(\dfrac{20}{90}\); \(\dfrac{4}{10}\) = \(\dfrac{4\times9}{10\times9}\) = \(\dfrac{36}{90}\)
Vì \(\dfrac{20}{90}\) < \(\dfrac{36}{90}\) vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)
b; \(\dfrac{4}{9}\) = \(\dfrac{4\times10}{9\times10}\) = \(\dfrac{40}{90}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times9}{10\times9}\) = \(\dfrac{54}{90}\)
Vì \(\dfrac{40}{90}\) < \(\dfrac{54}{90}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{6}{10}\)
c; \(\dfrac{3}{8}\) = \(\dfrac{3\times7}{8\times7}\) = \(\dfrac{21}{56}\); \(\dfrac{4}{7}\) = \(\dfrac{4\times8}{7\times8}\) = \(\dfrac{32}{56}\)
Vì \(\dfrac{21}{56}\) < \(\dfrac{32}{56}\) vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)
d; \(\dfrac{5}{9}\) = \(\dfrac{5\times10}{9\times10}\) = \(\dfrac{50}{90}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times9}{10\times9}\) = \(\dfrac{63}{90}\)
Vì \(\dfrac{50}{90}\) < \(\dfrac{63}{90}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)
\(a,A=3\times12+18\div(6+3)\)
\(\Rightarrow A=36+18\div9\)
\(\Rightarrow A=36+2\)
\(\Rightarrow A=38\)
a) 53,2 > 53, 19
b) 9,843 < 9, 85
c) 26,5 = 26,500
d) 80,6 > 79,6
Dễ
9 x 6 : 3 - 9 = 9