Question

sa se afle x din proportiile :
a) 3/×+4= 6/18
b) 3×-4/0,2 = 0,625/0,875
c) y+2/3×-2=30/24, unde y = nr prin care se verifică relația 5(y+1)=y+17
Va rog mult ​

Answer 1

a) 3/x+4=6/18=>3•18=6(x+4)=>54=6x+24=>6x=54-24=>

=>6x=30=>x=5

b) 3x-4/0,2=0,625/0,875=>5(3x-4)=5/7=>3x-4=5/7:5=>

=>3x-4=5/7•5=>3x-4=25/7=>3x=25/7+4(amplificăm prin 7) =>3x=25+28=>3x=53=>x=53/3

3x-4/0,2=>3x-4:0,2=3x-4:2/10=3x-4•10/2=(3x-4)•5

0,625/0,875=625/1000:875/1000=625/1000•1000/875=

=625/875(simplificăm prin 25)=25/35(simplificăm prin 5)=

=5/7

c) y+2/3x-2=30/24=>3+2/3x-2=30/24=>5/3x-2=30/24=>

=>5•24=30(3x-2) =>120=90x-60=> 90x-60=120=>9x=120+60=>9x=180=>x=180/9=>x=20

5(y+1)=y+17=>5y+5=y+17=>5y-y=17-5=>4y=12=>y=3