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Problem 41: Check whether or not the set $\V$ of all continuous functions $f$ on [0,1] sch that $f(\frac{3}{4})=1$, a vector space over $\R$ under pointwise addition and scalar multiplication.

Problem 41: Check whether or not the set $\V$ of all continuous functions $f$ on [0,1] sch that $f(\frac{3}{4})=1$, a vector space over $\R$ under pointwise addition and scalar multiplication.

Solution:
Let $f,g \in \V$ be any two members.
$\therefore f$ and $g$ are real-values continuous functions defined on [0,1] s.t
$f(\frac{3}{4})=1$ and $g(\frac{3}{4})=1$
Now, Then $f(\frac{3}{4})+g(\frac{3}{4}) = 1 + 1 = 2 \ne 1$
$\therefore f+g \notin \V$
$\Rightarrow \V$ is not closed under addition.

Hence, The $\V$ is not Vector space over $\R$.

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