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Các tỉ lệ thức có thể được là:
\(\dfrac{{14}}{{ - 10}} = \dfrac{{21}}{{ - 15}};\dfrac{{14}}{{21}} = \dfrac{{ - 10}}{{ - 15}};\dfrac{{ - 15}}{{ - 10}} = \dfrac{{21}}{{14}};\dfrac{{ - 15}}{{21}} = \dfrac{{ - 10}}{{14}}\)
A) 2.15 = 3.10
=>\(\frac{2}{3}\)= \(\frac{10}{15}\); \(\frac{2}{10}\)= \(\frac{3}{15}\);\(\frac{15}{3}\)= \(\frac{10}{2}\);\(\frac{15}{10}\)= \(\frac{3}{2}\)
B) 4,5.(-10) = -9.5
=> \(\frac{4,5}{-9}\)= \(\frac{5}{-10}\); \(\frac{4,5}{5}\)= \(\frac{-9}{-10}\); \(\frac{-10}{-9}\)=\(\frac{5}{4,5}\);\(\frac{-10}{5}\)=\(\frac{-9}{4,5}\)
\(a,\frac{0,25}{2}=\frac{0,5}{4}\)
b)\(\frac{4}{6}=\frac{10}{15}\)
a) \(\frac{0,25}{2}=\frac{0.5}{4}\)
b) \(\frac{4}{6}=\frac{10}{15}\)
hoặc \(\frac{4}{10}=\frac{6}{15}\)
\(\frac{2^{10}.9^{41}.25^{23}}{3^{50}.15^{35}.10^3}\)=\(\frac{2^{10}.\left(3^3\right)^{41}.\left(5^2\right)^{23}}{3^{50}.\left(3.5\right)^{35}.\left(2.5\right)^3}\)=\(\frac{2^{10}.3^{123}.5^{46}}{3^{50}.3^{35}.5^{35}.2^3.5^3}\)=\(\frac{2^{10}.3^{123}.5^{46}}{3^{85}.5^{38}.2^3}\)=\(2^7.3^{38}.5^8\)
Gọi ba số cần tìm lần lượt là a,b,c
Theo đề, ta có: \(\dfrac{a}{\dfrac{6}{5}}=\dfrac{b}{\dfrac{3}{2}}=\dfrac{c}{\dfrac{23}{10}}\)
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{a}{\dfrac{6}{5}}=\dfrac{b}{\dfrac{3}{2}}=\dfrac{c}{\dfrac{23}{10}}=\dfrac{a+b+c}{\dfrac{6}{5}+\dfrac{3}{2}+\dfrac{23}{10}}=\dfrac{15}{5}=3\)
Do đó: a=3,6; b=4,5; c=6,9
\(1)\)\(-\dfrac{10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)
\(=\dfrac{10}{11}\left(-\dfrac{8}{9}+\dfrac{7}{18}\right)\)
\(=\dfrac{10}{11}\left(\dfrac{-16}{18}+\dfrac{7}{18}\right)\)
\(=\dfrac{10}{11}.\left(-\dfrac{1}{2}\right)=-\dfrac{5}{11}\)
\(2)\)\(\dfrac{12}{25}.\dfrac{23}{7}-\dfrac{12}{7}.\dfrac{13}{25}\)
\(=\dfrac{12}{7}.\dfrac{23}{25}-\dfrac{12}{7}.\dfrac{13}{25}\)
\(=\dfrac{12}{7}.\left(\dfrac{23}{25}-\dfrac{13}{25}\right)\)
\(=\dfrac{12}{7}.\dfrac{2}{5}=\dfrac{24}{35}\)
\(3)\)\(\dfrac{3}{7}.\dfrac{16}{15}-\dfrac{2}{15}.\dfrac{-3}{7}\)
\(=\dfrac{3}{7}.\dfrac{16}{15}-\dfrac{3}{7}.\dfrac{-2}{15}\)
\(=\dfrac{3}{7}.\left(\dfrac{16}{15}+\dfrac{2}{15}\right)\)
\(=\dfrac{3}{7}.\dfrac{18}{15}=\dfrac{18}{35}\)
\(4)\)\(-\dfrac{4}{13}.\dfrac{5}{17}+\dfrac{-12}{13}.\dfrac{4}{17}\)
\(=-\dfrac{4}{13}.\dfrac{5}{17}+\dfrac{-4}{13}.\dfrac{12}{17}\)
\(=-\dfrac{4}{13}.\left(\dfrac{5}{17}+\dfrac{12}{17}\right)\)
\(=-\dfrac{4}{13}.\dfrac{17}{17}=-\dfrac{4}{13}\)
`#040911`
`1)`
`-10/11 * 8/9 + 7/18 . 10/11`
`= 10/11 * (-8/9 + 7/18)`
`= 10/11 * (-1/2)`
`= -5/11`
`2)`
`12/25 * 23/7 - 12/7 *13/25`
`= 12/7 * 23/25 - 12/7 * 13/25`
`= 12/7 * (23/25 - 13/25)`
`= 12/7 * 2/5`
`= 24/35`
`3)`
`3/7 * 16/15 - 2/15 * (-3)/7`
`= 3/7 * (16/15 + 2/15)`
`= 3/7 * 6/5`
`= 18/35`
`4)`
`-4/13 * 5/17 + (-12)/13 * 4/17`
`= -4/17 * 5/13 + (-12)/13 * 4/17`
`= 4/17 * (-5/13 - 12/13)`
`= 4/17 * (-17)/13`
`= -4/13`
Bài 1 : Ta thấy
\(\dfrac{10}{15}=\dfrac{2}{3};\dfrac{14}{21}=\dfrac{2}{3}\Rightarrow10:15=14:21\Rightarrow\dfrac{10}{15}=\dfrac{14}{21}\)
\(\dfrac{16}{\left(-4\right)}=-4;\dfrac{12}{\left(-3\right)}=-4\Rightarrow16:\left(-4\right)=12:\left(-3\right)\Rightarrow\dfrac{16}{\left(-4\right)}=\dfrac{12}{\left(-3\right)}=-4\)
\(\dfrac{\left(-5\right)}{15}=\dfrac{\left(-1,2\right)}{3,6}=-\dfrac{1}{3}\Rightarrow\left(-5\right):15=\left(-1,2\right):3,6\)
\(\dfrac{2}{3}:\dfrac{1}{4}=\dfrac{2}{3}.4=\dfrac{8}{3};\dfrac{16}{9}:\dfrac{16}{24}=\dfrac{16}{9}.\dfrac{24}{16}=\dfrac{8}{3}\)
\(\Rightarrow\left(\dfrac{2}{3}:\dfrac{1}{4}\right)=\left(\dfrac{16}{9}:\dfrac{16}{24}\right)=\dfrac{8}{3}\)
Bài 2 :
a) \(14.15=10.21\Rightarrow\dfrac{14}{10}=\dfrac{21}{15}=\dfrac{7}{5}\)
b) \(0,2.4,5=0,6.1,5\Rightarrow\dfrac{0,2}{0,6}=\dfrac{1,5}{4,5}=\dfrac{1}{3}\)
Bạn nên gõ đề bằng công thức toán (biểu tượng $\sum$ góc trái khung soạn thảo) để mọi người hiểu đề của bạn hơn.
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