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Dacă [tex] \frac{2x+5y}{x+y} [/tex] = 4,5 ,află :

a) [tex] \frac{x}{y} [/tex] = .................
b) [tex] \frac{5x}{2y} [/tex] = ....................
c) [tex] \frac{x ^{2}+ y^{2} }{ y^2}} [/tex] = ..............


Răspuns :

[tex] \frac{2x+5y}{x+y} =4,5[/tex]

[tex] \frac{2x+5y}{x+y} = \frac{45}{10} [/tex]

10*(2x+5y)=45*(x+y)
20x+50y=45x+45y
25x=5y
5x=y

a)x/y=1/5
b)5x/2y=5/2*1/5=1/2
c)[tex] \frac{ x^{2}+y^2}{y^2} = \frac{x^2}{y^2} + \frac{y^2}{y^2} =( \frac{x}{y} )^2+1= \frac{1}{25} +1= \frac{26}{25} [/tex]