Giải câu 4 bài nhị thức Newton.

$C_{5}^{0}-C_{5}^{1}+C_{5}^{2}-C_{5}^{3}+C_{5}^{4}-C_{5}^{5}=0(*)$

$VT(*)=\left( C_{5}^{0}-C_{5}^{5} \right)+\left( C_{5}^{4}-C_{5}^{1} \right)+\left( C_{5}^{2}-C_{5}^{3} \right)$

$=\left( C_{5}^{0}-C_{5}^{0} \right)+\left( C_{5}^{1}-C_{5}^{1} \right)+\left( C_{5}^{2}-C_{5}^{2} \right)$

$=0+0+0$

$=0=VP(*)$

$\Rightarrow $đpcm