diff --git a/content/notes/HW2.md b/content/notes/HW2.md index 64e1c1e00..b9633df77 100644 --- a/content/notes/HW2.md +++ b/content/notes/HW2.md @@ -30,11 +30,15 @@ Let $V$ be a vector space such that $dim(V)= 10$. Let $U$ and $W$ denote subspac (a). What is the max value of $dim(U\cap W)$, assuming $dim(U)=7$ and $dim(W)=4$ ? -From the formula $dim(U+W) = dim(U) + dim(W) - dim(U \cap W)$ we have $dim(U+W) = 7 + 4 - dim(U \cap W)$. +The largest possible dimension of $(U\cap W)$ is 4 which occurs when $W$ is entirely contained in $U$. -The largest possible dimension of $(U\cap W)$ is 4 which occurs when $W$ is entirely contained in $U$. So we have $dim(U\cap W) \leq 4$ hence the maximum pos$dim(U+W) = 7+4 - 4 +(b). What is the min value of $dim(U+W)$ +$dim(U\cap W) \leq 4$ so from the formula $dim(U+W) = dim(U) + dim(W) - dim(U \cap W)$ we have $dim(U+W) \geq 7 + 4 - 4= 7$. +(c). Max value of $dim(U+W)$ + +We have $dim(U+W) \leq dim(U) + dim(W) = 11$. But since $U+W$ is a subspace of $V$ which has dimension $10$ , we must have $dim(U+W) \leq 10$. # 3. Let $U$ = $\{p\in P_2(\mathbb{R}): p(x)$ is divisible by $x-3\}$. Then U is a subspace of P2