Tìm x :
( x - 1 ) + ( x - 2 ) + ( x - 3 ) + ... + ( x - 100 ) = -5750
=> ( x + x + x+..........+ x) - ( 1 + 2 + 3 + ........ + 100) = - 5750
=> 100x - \([\left(100+1\right).100:2]=-5750\)
=> 100x - ( 10100:2) = -5750
=> 100x - 5050 = -5750
=> 100x = -5750 + 5050
=> 100x = -700
=> x = -7
\(\left(x-1\right)+\left(x-2\right)+\left(x-3\right)+...+\left(x-100\right)=-5750\)
\(\Rightarrow x-1+x-2+x-3+...+x-100=-5750\)
\(\Rightarrow100x-\left(1+2+3+...+100\right)=-5750\)
\(\Rightarrow100x-\left[\left(\dfrac{100-1}{1}+1\right):2\right]\left(100+1\right)=-5750\)
\(\Rightarrow100x-5050=-5750\)
\(\Rightarrow100x=-200\)
\(\Rightarrow x=-2\)
