\(1-\dfrac{13}{19}=\dfrac{6}{19}\\ 1-\dfrac{47}{53}=\dfrac{6}{53}\\ \dfrac{6}{19}>\dfrac{6}{53}\Rightarrow\dfrac{13}{19}< \dfrac{47}{53}\)
Tính :
a, \(\dfrac{3\cdot13-13\cdot18}{15\cdot40-80}\);
b, \(\dfrac{18\cdot34+\left(-18\right)\cdot124}{-36\cdot17+9\cdot\left(-52\right)}\);
c, \(\dfrac{\dfrac{3}{41}-\dfrac{12}{47}+\dfrac{27}{53}}{\dfrac{4}{41}-\dfrac{16}{47}+\dfrac{36}{53}}+\dfrac{-0,25\cdot\dfrac{-2}{3}-0,75:\left(\dfrac{-1}{2}+\dfrac{2}{3}\right)}{\left|-1\dfrac{1}{2}\right|\cdot\left(\dfrac{-2}{3}-75\%:\dfrac{3}{-2}\right)}\).
So sánh A và B :
\(A=1.3.5.7.....99\)
\(B=\dfrac{51}{2}.\dfrac{52}{2}.\dfrac{53}{2}.....\dfrac{100}{2}\)
Bài 4: so sánh biểu thức A và B
a) A=\(\dfrac{19}{41}+\dfrac{23}{53}+\dfrac{29}{61}\)
B=\(\dfrac{21}{41}+\dfrac{23}{49}+\dfrac{33}{65}\)
b) C=\(\dfrac{19^{20}+5}{19^{20}-8}vàD=\dfrac{19^{21}+6}{19^{21}-7}\)
Tính:
\(\dfrac{7}{13}.\dfrac{5}{19}+\dfrac{7}{19}.\dfrac{8}{13}-3.\dfrac{7}{19}\)
P=\(\dfrac{20+\dfrac{19}{13}+\dfrac{19}{101}}{7+\dfrac{7}{13}+\dfrac{7}{19}+\dfrac{7}{101}}\)
Câu 1: So sánh:
a) \(\dfrac{-15}{17}và\dfrac{-19}{21}\)
b)\(\dfrac{-13}{19}và\dfrac{19}{-23}\)
c) \(\dfrac{-24}{35}và\dfrac{-19}{30}\)
d) \(\dfrac{-1941}{1931}và\dfrac{-2011}{2001}\)
\(\dfrac{14}{13}\) + (\(\dfrac{-1}{13}\) - \(\dfrac{19}{20}\))
Tính nhanh :
\(A=\dfrac{24.47-23}{24+47-23}.\dfrac{3+\dfrac{3}{7}-\dfrac{3}{11}+\dfrac{3}{1001}-\dfrac{3}{13}}{\dfrac{9}{1001}-\dfrac{9}{13}+\dfrac{9}{7}-\dfrac{9}{11}+9}\)
CMR 1.3.5...19=\(\dfrac{11}{2}.\dfrac{12}{2}.\dfrac{13}{2}...\dfrac{20}{2}\)
