\(x+1+x+2+x+3+x+4+x+5=140\)
\(5x+1+2+3+4+5=140\)
\(5x+15=140\)
\(x+3=28\)
\(x=25\)
Chúc em học tốt^^
5x + ( 1 + 2 + 3 + 4 + 5 ) = 140
5x + 15 = 140
5x = 140 - 15
5x = 125
x = 125 : 25
x = 5
(x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) = 140
=> (x + x + x + x + x) + (1 + 2 + 3 + 4 + 5) = 140
=> 5.x + (1 + 5).5:2 = 140
=> 5.x + 6.5:2 = 240
=> 5.x + 3.5 = 240
=> 5.x + 15 = 240
=> 5.x = 240 - 15 = 225
=> x = 225 : 5 = 45
(x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) = 140
x + x + x + x + x + 1 + 2 + 3 + 4 + 5 = 140
x + x + x + x + x + 15 = 140
x + x + x + x + x = 140 - 15
x + x + x + x + x = 125
x = 125 : 5
x = 25
(x+1)+(x+2)+(x+3)+(x+4)+(x+5)=140
x+x+x+x+x) + (1+2+3+4+5) =140
5x + 15 =140
5x =140:15
5x = 125
x =125:5
x = 25
Vậy x= 25.
(x+1)+(x+2)+(x+3)+(x+4)+(x+5)=140
5x + (1+2+3+4+5) = 140
5x + 15 = 140
5x = 140 - 15
5x = 125
x = 125 : 5
x = 25