Question

Найти неизвестный член пропорции: 1)х: 0,25=12: 0,75 2)0,36: 0,75=5: х 3)0,12: 0,5=х: 3 4)0,4: х=3,2: 4

Answer 1

1)х=0,25х12/0,75=3/0,75=4

2)х=0,75х5/0,36=3,75/0,36=10,416666

3)х=3х0,12/0,5=0,36/0,5=0,72

4)х=4х0,4/3,2=1,6/3,2=0,5 

Answer 2

1) $x:0,25=12:0,75$

$\frac{x}{0,25}=\frac{12}{0,75}$

$x=\frac{0,25\cdot12}{0,75}=\frac{3}{0,75}=4$

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$4:0,25=12:0,75$ (это проверка)

$16=16$

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2) $0,36:0,75=5:x$

$\frac{0,36}{0,75}=\frac{5}{x}$

$\frac{36}{75}=\frac{5}{x}$

$\frac{12}{25}=\frac{5}{x}$

$x=\frac{5\cdot25}{12}=\frac{125}{12}=10\frac{5}{12}$

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 $0,36:0,75=5:10\frac{5}{12}$

$\frac{36}{75}=5:\frac{125}{12}$

$\frac{12}{25}=5\cdot\frac{12}{125}$

$0,48=0,48$

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3) $0,12:0,5=x:3$

$\frac{0,12}{0,5}=\frac{x}{3}$

$x=\frac{3\cdot0,12}{0,5}=\frac{0,36}{0,5}=0,72$

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$0,12:0,5=0,72:3$

$0,24=0,24$

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4) $0,4:x=3,2:4$

$\frac{0,4}{x}=\frac{3,2}{4}$

$x=\frac{0,4\cdot4}{3,2}=\frac{1,6}{3,2}=0,5$

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$0,4:0,5=3,2:4$

$0,8=0,8$