Question

doar a),b),c) dau coroana​

Answer 1

Răspuns:

Explicație pas cu pas:

a) 1,25·[0,(6)x-0,4]=x  ⇒125/100·(6x/9-4/10)=x  ⇒125/100·(2x/3-2/5)=x  ⇒125/100·(10x-6)/15=x  ⇒125·(10x-6)/100·15=x  ⇒125·(10x-6)=100·15·x  ⇒

1250x-750=1500x  ⇒-750=250x  ⇒x=-750/250=-3   x=-3

b) 1,2·[0,(3)x+0,74]=x  ⇒12/10·(3x/9+74/100)=x  ⇒6/5·(x/3+37/50)=x  

⇒6/5·(50x+111)/150=x  ⇒6·(50x+111)/5·150=x  ⇒6·(50x+111)=5·150·x  ⇒300x+666=750x  ⇒666=450x  ⇒x=666/450=222/150=111/75=37/25  ⇒x=37/25

c) 0,4·[1,(6)x+1,25]=x  ⇒4/10·(15x/9+125/100)=x  ⇒2/5·(5x/3+5/4)=x  ⇒

2/5·(20x+15)/12=x  ⇒2·(20x+15)/5·12=x  ⇒2·(20x+15)=5·12·x  ⇒40x+30=60x  ⇒30=20x  ⇒x=30/20=3/2  ⇒x=3/2

d) 2,5·[0,1(3)x-0,16]=x  ⇒25/10·(12x/90-16/100)=x  ⇒5/2·(2x/15-4/25)=x  ⇒

5/2·(10x-12)/75=x  ⇒5·(10x-12)/2·75=x  ⇒5·(10x-12)=2·75·x  ⇒50x-60=150x  ⇒-60=100x  ⇒x=-60/100=-6/10=-3/5   ⇒x=-3/5