Solution to #1-6

Paper 1 Difficulty: Easy

Solve the following sum:

$latex \sum_{n=1}^{100}2n+3$

[Maximum mark: 2]

$latex \sum_{n=1}^{100}2n+3 = 2\sum_{n=1}^{100}n + \sum_{n=1}^{100}3$

We apply the formula $latex \sum_{n=1}^{100}n = \frac{n \left ( n+1 \right ) }{2} = 5050$.

So $latex \sum_{n=1}^{100}2n+3 = 2 \cdot 5050 + 3 \cdot 100 = 10400$.


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