Tìm x trong tỉ lệ thức, làm bằng 2 cách a, 2,5 : 7,5 = x : 3/5 b, 2 2/5 : x = 1 1/7 : 0,2 Chú ý: +Làm bằng hai cách + 2 2/5 và 1 1/7 là hỗn số

Bạn tham khảo nhé!

$a)$ $2,5$ $:$ $7,5$ $=$ $x$ $:$ $\dfrac{3}{5}$
$C_{1}$ : $\dfrac{1}{3}$ $=$ $x$ $:$ $\dfrac{3}{5}$
$x$ $=$ $\dfrac{1}{3}$ $.$ $\dfrac{3}{5}$
$x$ $=$ $\dfrac{1}{5}$
$C_{2}$ : $\dfrac{2.5}{7.5}$ $=$ $\dfrac{x}{0.6}$
$→$ $7.5$ $.$ $x$ $=$ $2,5$ $.$ $0.6$
$→$ $7.5$ $.$ $x$ $=$ $\dfrac{3}{2}$
$→$ $x$ $=$ $\dfrac{3}{2}$ $:$ $7.5$
$→$ $x$ $=$ $\dfrac{1}{5}$
$b)$ $2$ $\dfrac{2}{5}$ $:$ $x$ $=$ $1$ $\dfrac{1}{7}$ $:$ $0.2$
$→$ $\dfrac{12}{5}$ $:$ $x$ $=$ $\dfrac{8}{7}$ $:$ $0.2$
$C_{1}$ : $\dfrac{12}{5}$ $:$ $x$ $=$ $\dfrac{40}{7}$
$x$ $=$ $\dfrac{12}{5}$ $:$ $\dfrac{40}{7}$
$x$ $=$ $\dfrac{21}{50}$
$C_{2}$ : $\dfrac{2.4}{x}$ $=$ $\dfrac{8/7}{0.2}$
$→$ $2.4$ $.$ $0.2$ $=$ $x$ $.$ $\dfrac{8}{7}$
$→$ $\dfrac{12}{25}$ $=$ $x$ $.$ $\dfrac{8}{7}$
$→$ $x$ $=$ $\dfrac{21}{50}$
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