FACTORISE THIS QUADRATIC PLEASE!?

This is easy because of the missing constant term. 3u² + u = u(3u + 1) = 0 is the factored form on the given equation. The two solutions are u = 0 and (3u + 1) = 0. The second solution is u = -1/3.

3u(u-1/3)=0

so u can be 0 or u can be 1/3

u (3u + 1) = 0
u = 0 , u = - 1/3

(3u+1)(u) = 0 =>
u = 0 or u = -1/3.

u(3u+1)=0
u=0 u=-1/3