Question

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

Answer 1

(x + 1) + ( x + 2 ) + . . . . . . . . + (x + 100) = 5750=> x + 1 + x + 2 + x + 3 + . . . . . . .. . .. . . . + x + 100 = 5750=> ( 1 + 2 + 3 + . . . + 100) + ( x + x + x ngoặc này có 100x . . . . . . + x ) = 5750 =>((100+1).100)/2 +100x => 5050+100x=5750 => 100x=700 => x=7

Answer 2

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

=> (x + x + x +...... +x) + (1 + 2 + 3 + 4 + ... + 100) = 5750    

=> 100x + 5050 = 5750

=> 100x = 5750 - 5050

=> 100x = 700

=> x = 700 : 100

=> x = 7