Explicatie:
Intr-o proportie produsul mezilor = produsul extremilor.
[tex]\displaystyle\bf\\6a)~~\frac{x}{6}=\frac{9}{27}\implies x=\frac{6\times9}{27}=\frac{54}{27}=2\\\\\\6b)~~\frac{2}{3}=\frac{6}{y}\implies y=\frac{3\times6}{2}=\frac{18}{2}=9\\\\\\6c)~~\frac{0,\!5}{3}=\frac{6}{z}\implies z=\frac{3\times6}{0,\!5}=\frac{18}{0,\!5}=36\\\\\\ 6d)~~\frac{a}{1,\!2}=\frac{10}{3}\implies a=\frac{1,\!2\times10}{3}= \frac{12}{3}=4[/tex]
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[tex]\displaystyle\bf\\6e)~~\frac{2,\!1}{b}=\frac{7}{4}\implies b=\frac{2,\!1\times4}{7}=\frac{8,\!4}{7}=1,\!2 \\\\\\6f)~~\frac{1,\!8}{u}=\frac{1,\!12}{2,\!52}\implies b=\frac{1,\!8\times2,\!52}{1,\!12} =\frac{4,536}{1,\!12}=4,\!05\\\\\\6g)~~\frac{x+3}{6} =\frac{5}{2}\implies x+3=\frac{6\times5}{2}=\frac{30}{2} =15\implies~x=15-3=12\\\\\\6h)~~\frac{27}{42}=\frac{45}{7\cdot x}\implies 7\cdot x=\frac{42\cdot45}{27} =\frac{1890}{27}=70\implies x=\frac{70}{7}=10[/tex]
