ĐK: $x\geq 2Pt\Leftrightarrow C^x_{x+1}+C^{x-1}_{x+1}=C^{2x-3}_{x+2}⇔Cxx+2=C2x−3x+2\Leftrightarrow x=2x-3\Leftrightarrow x=3$
ĐK: $
2\leq x\
leq
5Pt\Leftrightarrow C^x_{x+1}+C^{x-1}_{x+1}=C^{2x-3}_{x+2}
⇔Cxx+2=C2x−3x+2\Leftrightarrow x=2x-3\Leftrightarrow x=3$