# Math Help - rank nullity and linear transformation

1. ## rank nullity and linear transformation

Hi So i am getting to the end of the material , and again I find one of the assignments I am supposed to understand saying left to the reading

I really would like to see the proof to this a it would be really helpful

2. ## Re: rank nullity and linear transformation

do you know the rank-nullity theorem?

3. ## Re: rank nullity and linear transformation

Yes it's
rank A + nullity A = n
Where n is the Number of col

4. ## Re: rank nullity and linear transformation

Correct, now plugging in $\text{rk}(A)=\text{null}(A)$ to the rank-nullity theorem gives $n=2\text{rk}(A)$.