Question

tím số tự nhiên x , biết rằng

(x+1)+(x+2)+(x+3)+...(x+100)=5750

Answer 1

(x+1)(x+2)+(x+3)+...+(x+100)=5750

(x+x+...+x)(1+2+3+...+100)=5750

100x         +          5050 =5750

 100x                             =700

 x                                   =7         

Answer 2

( x + 1 ) + ( x + 2 ) + ( x + 3 ) + ... + ( x + 100 ) = 5750

( x + x + x + ... + x ) + ( 1 + 2 + 3 + ... + 100 ) = 5750

x . 100 + ( 100 + 1 ). 100 : 2 =5750

x .100 + 5050 = 5750

x .100 = 5750 - 5050

x . 100 = 700

x = 700 : 100

x = 7