# Kernal and Range of a Linear Transformation

by hkus10
Tags: kernal, linear, range, transformation
 P: 50 Let L:p2 >>> p3 be the linear transformation defined by L(p(t)) = t^2 p'(t). (a) Find a basis for and the dimension of ker(L). (b) Find a basis for and the dimension of range(L). The hint that I get is to begin by finding an explicit formula for L by determining L(at^2 + bt + c). Does this hint mean let p(t) = at^2 + bt + c? Then, I find that t^2 p'(t) = 2at^3 + bt^2. Then, I conclude that the basis for ker(L) = {1}. Is it right? Also, how to find range(L)? Thanks
 HW Helper P: 1,584 Factorise... $$L(at^{2}+bt+c)=2at^{3}+bt^{2}=t^{2}(2at+b)$$ This will be zero when t=0 or t=-b/2a, so...
HW Helper
Thanks
P: 25,011
 Quote by hunt_mat Factorise... $$L(at^{2}+bt+c)=2at^{3}+bt^{2}=t^{2}(2at+b)$$ This will be zero when t=0 or t=-b/2a, so...
That doesn't have much to do with the problem. hkus10 correctly has ker(L)={1} and having written L(p(t))=2at^3+bt^2 the answer to the dimension and a basis of range(L) should be pretty obvious. Why isn't it hkus10? What's a basis for p3?

P: 50

## Kernal and Range of a Linear Transformation

is the basis for ker(L) {t, 1} and the basis for range(L) {t^3, t^2}?
HW Helper
Thanks
P: 25,011
 Quote by hkus10 is the basis for ker(L) {t, 1} and the basis for range(L) {t^3, t^2}?
Two steps forward, one step backward. Yes, that's a basis for range(L). But now your basis for ker(L) is wrong. I liked your ker(L)={1} a lot better. Why did you put t in? Is t in the kernel?
PF Gold
P: 1,930
 Quote by hkus10 is the basis for ker(L) {t, 1} and the basis for range(L) {t^3, t^2}?
I believe you have a workable basis for range(L). However, I think your basis for ker(L) has too many entries.
 P: 50 Since L(at^2 + bt + c) = 2at^3 + bt^2 No matter what value of t and 1, 2a^3 + bt^2 should always give me 0 vector. So, I have a question why Ker(L) does not have t as a basis? Another question is dim Ker(L) + dim range(L) = dim (p3) by thm. since the dim range(L) = 2 and dim (p3) = 4, why dim ker(L) not equal to 2?