Prove by induction that the recurrence form of bubble sort is $\Omega(n^2)$


The recurrence form of bubble sort is $ T(n)=T(n-1)+ n- 1$

How can I prove by induction that this is $ \Omega(n^2)$ ?

I’m stuck with $ T(n+1) \geq cn^2 + n = n(cn+1)$