Expand (p−2q+r)2
The correct option is A p2+4q2+r2−4pq−4qr+2rp
Using (a+b+c)2=a2+b2+c2+2ab+2bc+2ac,
Here a=p,b=−2q and c=r
∴(p−2q+r)2=(p)2+(−2q)2+(r)2+2(p)(−2q)+2(−2q)(r)+2(p)(r)
=p2+4q2+r2−4pq−4qr+2pr
Hence, (p−2q+r)2=p2+4q2+r2−4pq−4qr+2pr