Question

rezolvati in multimea Q ecuatia:
a) 2,3x+1,2x=7
b) 1-1/5x=0,5
c) 5-2x=-2,6.

Answer 1

a) 3,5x=7
x=7:3,5=7/1:35/10=7/1·10/35=70/35=2
x=2

b) 1-(1/5)x=0,5
1-x/5=0,5
x/5=0,5-1
x/5=-0,5
x=-0,5·5
x=-2,5

c) -2x=-2,6-5
-2x=-7,6    inm,ultim -1
2x=7,6
x=7,6:2
x=76/10:2/1=76/10·1/2=76/20=3,8
x=3,8

Answer 2

a)2,3=23/10,1,2=12/10⇒23x/10+12x/10=7⇒35x/10=7⇒35x=70⇒x=2
b)1-1/5x=0,5     0,5=5/10=1/2⇒1-1/5x=1/2   vom aduce fractiile la acelasi numitor si vom avea:10-2x=5⇒2x=10-5⇒2x=5⇒x=5/2
c)2,6=26/10=13/5⇒5-2x=13/5  vom aduce la acelasi numitor si avem:
25-10x=13⇒10x=25-13⇒10x=12⇒x=12/10=6/5