1) 1km........................100000cm
200km...................x cm
c=20000000 cm
2)[tex] \frac{a}{b} = \frac{c}{d} => bc=ad[/tex]
7-[tex] \frac{ab}{bc}=7- \frac{ab}{ad}=7- \frac{b}{d} [/tex]
cred ca asa e
3) a)[tex] \frac{4}{1} = \frac{36}{9} [/tex]
b)nu e bun exercitiul...poate ai dat numerele gresit... dar oricum ai pune numerele nu da egal
4) a) [tex] \frac{x}{5} = \frac{8}{7}=> x= \frac{8*5}{7}=> x= \frac{40}{7} [/tex]
b)[tex] \frac{2}{x}= \frac{3}{4}=> x= \frac{2*4}{3} => x= \frac{8}{3} [/tex]
c)[tex]\frac{x}{x}+2= \frac{4}{5} | *x [/tex]
[tex]x+2x= \frac{4x}{5} |*5 [/tex]
[tex]15x=4x[/tex]
15x-4x=0
x(15-4)=0
x=0
5) 6 muncitori.................12 zile
8 muncitori...................x zile ( marimi invers proportionale)
x=[tex] \frac{6*12}{8}=9[/tex]
vor termina in 9 zile
6){x;y}d.p.{5;7}⇒[tex] \frac{x}{5}= \frac{y}{7} =>7x=5y=> x= \frac{5y}{7} [/tex]
[tex] m_{a}= \frac{x+y}{2} = \frac{1}{2} *(y+ \frac{5y}{7} )= \frac{1}{2} * \frac{12y}{7} = \frac{6y}{7} [/tex]
[tex] \frac{294}{10}= \frac{6y}{7} => 60y=2058=> y= \frac{2058}{60} [/tex]
[tex]x= \frac{1}{7}* \frac{2058}{60} =>x= \frac{294}{60} => x= \frac{49}{10} [/tex]
