Given: αandβ be the roots of equation px2+qx−r=0
So, α+β=−pq,αβ=−pr
It is given that, α1+β1=43
⇒αβα+β=43
⇒rq=43
Now, p,q,r are in GP
So, common ratio of this GP will be pq=qr=34
⇒px2+qx−r=0
⇒x2+pqx−pr=0
⇒x2+34x−(34)2=0
⇒9x2+12x−16=0
⇒(α−β)2=(α+β)2−4αβ
⇒(α−β)2=(9−12)2−4(9−16)
⇒(α−β)2=916+964
⇒(α−β)2=980