Motion in a Plane

A particle starts from origin at t=0 with a velocity 5

^

i

m∕ s and moves in x−y plane under action of a force which produces a constant acceleration of (3

^

i

+2

^

j

)m∕ s2. If the x-coordinate of the particle at that instant is 84m, then the speed of the particle at this time is √αm∕ s. The value of α is____