Răspuns:
1. a) se aduce la acelasi numitor 6
2*(x+2) + 3 *1= x+10 => 2x +4 + 3= x+ 10
2x- x= 10-7 x= 3
b) [tex]\frac{11}{4}[/tex] - [tex]\frac{1}{6}[/tex] - [tex]\frac{13}{12}[/tex] = [tex]\frac{33-2-13}{12}[/tex]=[tex]\frac{18}{12}[/tex] = [tex]\frac{3}{4}[/tex]
c)( [tex]\frac{1}{6}[/tex] + 1+ [tex]\frac{1}{3}[/tex] -[tex]\frac{1}{3}[/tex]- [tex]\frac{1}{9}[/tex])*9 =([tex]\frac{1}{6}[/tex] +1 -[tex]\frac{1}{9}[/tex]) *9= [tex]\frac{9}{6}[/tex] +9 - [tex]\frac{9}{9}[/tex]= [tex]\frac{3}{2}[/tex] +9-1 =[tex]\frac{3}{2}[/tex] +8= [tex]\frac{3+16}{2}[/tex]= [tex]\frac{19}{2}[/tex]
d) [tex]\frac{2x}{7}[/tex] - [tex]\frac{1}{2}[/tex]=[tex]\frac{5}{14}[/tex] aducem la acelasi numitor 14
4x -7= 5 => 4x= 5+7 4x=12 => x= 12:4= 3 x= 3
2. a= [tex]\frac{1}{2}[/tex]*t b= [tex]\frac{1}{3}[/tex]*R c= 120lei |______|__|____| total
a= prima zi, b= a 2-a zi c= a treia zi R= rest
c=[tex]\frac{2R}{3}[/tex] 120 = [tex]\frac{2R}{3}[/tex] => R= 3x120: 2= 360: 2=180 lei ( restul ( ultimele 2 zile)
b= R/3= 180: 3= 60lei ( a doua zi)
t= 2R= 2x 180= 360 lei ( total)
a= t/2 = 360:2= 180 lei ( prima zi)
