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\(a.14,52\div1,5-9,81\div1,5\)
\(=\left(14,52-9,81\right)\div1,5\)
\(=4,71\div1,5=3,14\)
\(b.\frac{5}{9}:\frac{4}{7}+\frac{13}{9}\times\frac{7}{4}\)
\(=\frac{5}{9}\times\frac{7}{4}+\frac{13}{9}\times\frac{7}{4}\)
\(=\left(\frac{5}{9}+\frac{13}{9}\right)\times\frac{7}{4}\)
\(=\frac{18}{9}\times\frac{7}{4}\)
\(=2\times\frac{7}{4}\)
\(=\frac{7}{2}\)
14,52:1,5-9,81:1,5=( 14,52-9,81 ) : 1,5
=4,71:1,5
=3,14
con thứ 2 thì mình chịu, bạn tự làm nha.
học tốt lên nhé. mình chỉ biết làm luôn thôi nhé.
a) 14,25 : 1,5 - 9,81 : 1,5 = (14,25 - 9,81) : 1,5
= 4,44 : 1,5
= 2,96
b) \(\frac{5}{9}\): \(\frac{4}{7}+\frac{13}{9}\) * \(\frac{7}{4}\) = \(\frac{5}{9}\cdot\frac{7}{4}+\frac{13}{9}\cdot\frac{7}{4}\)
= \(\left(\frac{5}{9}+\frac{13}{9}\right)\cdot\frac{7}{4}\)
= 2 \(\cdot\frac{7}{4}\)
= \(\frac{7}{2}\)
\(\frac{16x17-5}{16x16+11}=\frac{16x16+16-5}{16x16+11}=1\)
\(\frac{4}{3x7}+\frac{5}{7x12}+\frac{1}{12x13}+....+\frac{3}{20x23}\)
=\(\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{12}+\frac{1}{12}-\frac{1}{13}+...+\frac{1}{20}-\frac{1}{23}\)
=\(\frac{1}{3}-\frac{1}{23}=\frac{20}{69}\)
a) \(\frac{16\cdot17-5}{16\cdot16+11}\)
= \(\frac{16\cdot16+16-5}{16\cdot16+11}\)
= \(\frac{16\cdot16+11}{16\cdot16+11}=1\)
a) \(\dfrac{1}{9}\times\dfrac{4}{7}+\dfrac{1}{9}\times\dfrac{3}{7}=\dfrac{1}{9}\times\left(\dfrac{4}{7}+\dfrac{3}{7}\right)=\dfrac{1}{9}\times1=\dfrac{1}{9}\)
b) \(\dfrac{5}{13}\times\dfrac{189}{18}-\dfrac{5}{13}\times\dfrac{9}{18}=\dfrac{5}{13}\times\left(\dfrac{189}{18}-\dfrac{9}{18}\right)=\dfrac{5}{13}\times\dfrac{180}{18}=\dfrac{5}{13}\times10=\dfrac{50}{13}\)
c) \(\dfrac{12}{7}:\dfrac{4}{9}+\dfrac{4}{7}:\dfrac{4}{9}=\dfrac{12}{7}\times\dfrac{9}{4}+\dfrac{4}{7}\times\dfrac{9}{4}=\left(\dfrac{12}{7}+\dfrac{4}{7}\right)\times\dfrac{9}{4}=\dfrac{16}{7}\times\dfrac{9}{4}=\dfrac{144}{28}=\dfrac{36}{7}\)
\(A=\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+...+\frac{1}{9.11}-\frac{1}{11.13}\)
\(\Leftrightarrow A=\frac{1}{1.3}-\frac{1}{11.13}=\frac{1}{3}-\frac{1}{143}=\frac{140}{429}\)
\(A=\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+\frac{4}{7.9.11}+\frac{4}{9.11.13}\)
\(\Rightarrow A=\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+...+\frac{1}{9.11}-\frac{1}{11.13}\)
\(\Rightarrow A=\frac{1}{1.3}-\frac{1}{11.13}=\frac{1}{3}-\frac{1}{143}=\frac{140}{429}\)
a) 47/15
b)77/9