Tìm x biết: (x + 1) + (x + 2) + (x + 3) + ... + (x + 100) = 5750
Giải thích
(x + 1) + (x + 2) + (x + 3) + ... + (x + 100) = 5750
100x + ( 1 + 2 + 3 + … + 100) = 5750
\[100x + \frac{{\left( {1 + 100} \right).100}}{2} = 5750\]
100x + 5050 = 5750
100x = 5750 – 5050
100x = 700
x = 700 : 100
x = 7
Vậy x = 7.