Question

If f : R$\rightarrow$ R satisfies f (x + y) = f (x) + f ( y) , for all x, y ∈ R and f(1) = 7, then $\underset{r=1}{\overset{n}{\sum}}f(r)$ is
[tex](a) \frac{7n(n +1)}{2} \\
(b) \frac{7n}{2} \\
(c) \frac{7(n + 1)}{2} \\
(d) 7n +(n + 1)[/tex]

Answer 1

Answer:

Step-by-step explanation:

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