=>-1+(3-5)+(7-9)+...+[(x-4)-(x-2)]+x=600
=>-1+(-2)+(-2)+...+(-2)+x=600 (\(\frac{x-1}{4}\) số hạng -2)
=>-1+(-2)\(\frac{x-1}{4}\)+x=600
=>\(\frac{-4+\left(-2\right)\left(x-1\right)+4x}{4}=600\)
=>-4+(-2)(x-1)+4(x-1)+4=600.4
=>(-2+4)(x-1)=2400+4-4
=>2(x-1)=2400
=>x-1=2400:2
=>x-1=1200
=>x=1201