Question

aflati numarul natural a din proportiile a)3/7=a\28 b)a/2=7/3,5 c)4/a=a/9 d) 0,6/2·a=0,9/21

Answer 1

Răspuns:

Explicație pas cu pas:

a)

$\frac{3}{7} = \frac{a}{28} \Longrightarrow a = \frac{3 \times 28}{7} = \frac{84}{7} = \blue{\bf{} 12}$

b)

$\frac{a}{2} = \frac{7}{3,5} \Longrightarrow a = \frac{7 \times 2}{3,5} = \frac{14}{3,5} =\blue{ \bf{} 4 }$

c)

$\frac{4}{a} = \frac{a}{9} \Longrightarrow a {}^{2} = 4 \times 9 = 36 \Longrightarrow a = \sqrt{36} = \blue{\bf{} 6}$

d)

$\frac{0,6}{2a} = \frac{0,9}{21}$

$2 \times a \times 0,9 = 0,6 \times 21$

$1,8\times a = 12,6 \Longrightarrow a = \frac{12,6}{1,8} = \blue{\bf{} 7}$