The correct option is A 20C102
We know that,
(1+x)20= 20C0+ 20C1x+ 20C2x2+ 20C3x3+…+ 20C20x20
Putting x=−1, we get
20C0− 20C1+ 20C2− 20C3+…+ 20C20=0⇒2( 20C0− 20C1+ 20C2− 20C3+…)+ 20C10=0(∵ 20Cr= 20C20−r)⇒( 20C0− 20C1+ 20C2− 20C3+…)=− 20C102∴ 20C0− 20C1+ 20C2− 20C3+…+ 20C10= 20C102