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\(\dfrac{2\times3\times5}{4\times9\times10}=\dfrac{2\times3\times5}{2^2\times3^2\times2\times5}=\dfrac{1}{2^2\times3}=\dfrac{1}{12}\)
\(\dfrac{2\text{×}3\text{×}5}{4\text{×}9\text{×}10}=\dfrac{2\text{×}3\text{×}5}{2\text{×}2\text{×}3\text{×}3\text{×}2\text{×}5}=\dfrac{1}{2\text{×}3\text{×}2}=\dfrac{1}{12}\)
a)\(\frac{7x9x12}{6x14x18}=\frac{7x9x6x2}{6x7x2x9x2}=\frac{2}{2x2}=\frac{1}{2}\)
b) \(\frac{2x3x5}{4x9x10}=\frac{2x3x5}{2x2x3x3x2x5}=\frac{1}{2x2x3x5}=\frac{1}{60}\)
1. Rút gọn
\(\frac{8x20x4}{9x20x4}=\frac{8}{9}\)
\(\frac{7x9x12}{6x14x18}=\frac{1x1x2}{1x2x2}=\frac{2}{4}=\frac{1}{2}\)
\(\frac{2x3x5}{4x9x10}=\frac{1x1x1}{2x3x2}=\frac{1}{12}\)
2. tìm x
\(\frac{x}{27}=\frac{12}{18}\)
\(\frac{x}{27}=\frac{2}{3}\)
=> X x 3 = 27 x 2
X x 3 = 54
X = 54 : 3
X = 18
\(\frac{35}{49}=\frac{10}{x}\)
\(\frac{5}{7}=\frac{10}{x}\)
=> 5 x X = 7 x 10
5 x X = 70
X = 70 : 5
X = 14
1. \(\frac{8.20.4}{9.20.4}\)= \(\frac{8}{9}\)
\(\frac{7.9.12}{6.14.18}\)= \(\frac{7.9.6.2}{6.7.2.9.2}\)= \(\frac{1}{2}\)
\(\frac{2.3.5}{4.9.10}\)= \(\frac{2.3.5}{2.2.3.3.2.5}\)= \(\frac{1}{12}\)
2. \(\frac{x}{27}\)= \(\frac{12}{18}\) \(\frac{35}{49}\)= \(\frac{10}{x}\)
Ta có : \(\frac{12}{18}\)= \(\frac{6}{9}\) Ta có : \(\frac{35}{49}\)= \(\frac{70}{98}\)
Mà \(\frac{x}{27}\)= \(\frac{6}{9}\) Mà \(\frac{10}{x}\)= \(\frac{70}{98}\)
\(\Rightarrow\)\(x\)= \(27:9.6\) \(\Rightarrow\)\(x\)= \(98:\left(70:10\right)\)
Chú ý : '' \(.\)" là dấu nhân.
\(\frac{30\cdot25\cdot7\cdot8}{75\cdot8\cdot12\cdot14}\)
\(=\frac{2\cdot3\cdot5\cdot5\cdot5\cdot7\cdot8}{5\cdot3\cdot5\cdot8\cdot3\cdot2\cdot2\cdot2\cdot7}\)
\(=\frac{5}{3\cdot2\cdot2}\)
\(=\frac{5}{12}\)
\(\frac{2\cdot3\cdot5}{20\cdot6}\)
\(=\frac{2\cdot3\cdot5}{4\cdot5\cdot2\cdot3}\)
\(=\frac{1}{4}\)
\(\frac{30\times25\times7\times8}{75\times8\times12\times14}=\frac{6\times5\times25\times7\times8}{3\times25\times8\times6\times2\times7\times2}=\frac{5}{3\times2\times2}=\frac{5}{12}\)
\(\frac{2\times3\times5}{20\times6}=\frac{2\times3\times5}{4\times5\times3\times2}=\frac{1}{4}\)
~Học tốt ~~
\(\frac{2x3x5}{70}\)= \(\frac{2x3x5}{2x5x7}\)= \(\frac{3}{7}\)
Đây là cách làm của bài này
Chúc bạn học tốt!
\(\frac{2x3x5}{70}=\frac{2x3x5}{2x5x7}=\frac{3}{7}\)
Các bạn ủng hộ mk nha
\(\dfrac{2\times3\times5}{4\times9\times10}\)
\(=\dfrac{2\times3\times5}{2\times2\times3\times3\times5\times2}\)
\(=\dfrac{1}{2\times3\times2}=\dfrac{1}{12}\)
a. 6 x 5 = 30
b.4 x 9 x 10 = 36 x 10 = 360