Question

determinati x E N* ,astfel incat observati fractii echiunitare: a) 2/3= 21/x b)x/9=40/72

Answer 1

a)
$\frac{2}{3} = \frac{21}{x} \\ \\ \frac{3}{2}=\frac{x}{21} \\ \\ x=\frac{63}{2}=31,5$
Dar 31,5 nu este natural, deci nu exista solutii

b)
$\frac{x}{9}=\frac{40}{72} \\ \\ x=\frac{40\cdot9}{72} \\ \\ x=\frac{360}{72}=5$