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Aflați valorile rapoartelor: a)7x+2y/2x+3y unde x/y=0,2
b)14x-5y/8x+3y unde y=x/0,(6)
c)5x-2+15y/3x+4+9y unde 3y= 1-x


Răspuns :

Răspuns:

Explicație pas cu pas:

Aflați valorile rapoartelor:

a) 7x+2y/2x+3y unde x/y=0,2

x/y=0,2  ⇔ x=0,2y  

(7x+2y)/(2x+3y)=(7·0,2y+2y)/(2·0,2y+3y)=(1,4y+2y)/(0,4y+3y)=3,4y/3,4y=1

b) 14x-5y/8x+3y unde y=x/0,(6)

y=x/0,(6)  ⇔ y=x/(6/9)  ⇔ y=x/(2/3)  ⇔ y=3x/2

(14x-5y)/(8x+3y)=(14x-5·3x/2)/(8x+3·3x/2)=(2·14x-15x)/2/(2·8x+9x)/2=

(13x/2)/(25x/2)=13x/25x=13/25      

c) 5x-2+15y/3x+4+9y unde 3y= 1-x

(5x-2+15y)/(3x+4+9y)=(5x-2+5·3y)/(3x+4+3·3y)=[5x-2+5·(1-x)]/[3x+4+3(1-x)]=

(5x-2+5-5x)/(3x+4+3-3x)=3/7