( x+ 1 ) + ( x + 2 ) + ( x + 3 ) + ( x + 4 ) + ( x + 5 ) = 40
x + ( 1 + 2 + 3 + 4 + 5 ) = 40
x + 15 = 40
x = 25
( x+ 1 ) + ( x + 2 ) + ( x + 3 ) + ( x + 4 ) + ( x + 5 ) = 40
x + ( 1 + 2 + 3 + 4 + 5 ) = 40
x + 15 = 40
x = 25
( x + 1 ) + ( x + 2 ) + ( x + 3 ) + ( x + 4 ) + ( x + 5 ) = 40
=> x + ( 1 + 2 + 3 + 4 + 5 ) = 40
=> x + 15 = 40
=> x = 40 - 15
=> x = 25
Chúc bn học giỏi ^^
(x+1)+(x+2)+(x+3)+(x+4)+(x+5)=40
x+(1+2+3+4+5)=40
x+15=40
x =40-15
x =25
( x + 1 ) + ( x + 2 ) + ( x + 3 ) + ( x + 4 ) + ( x + 5 ) = 40
x + ( 1 + 2 + 3 + 4 + 5 ) = 40
x + 15 = 40
x = 25