A reaction is first order in A and second order in B. How is rate affected when concentration of B is tripled?

Rate increases by nine times

rate = K [A]¹ [B]²
(ii) Rate, r₁ = K [A]¹[B]² …………… (i)
When concentration of B is increased three times then
Rate, r₂ = K [A]¹ [3B]² ………..(ii)
Dividing equation (ii) by (i) we get
r₂ = 9r₁ rate increases by nine times.