Question 5
In the following expression, Melanie changed some of the plus signs to minus signs:
$$
1 + 3 + 5 + 7 + \cdots + 97 + 99
$$
When the new expression was evaluated, it was negative. What is the least number of plus signs that Melanie could have changed to minus signs?
$$
1 + 3 + 5 + 7 + \cdots + 97 + 99
$$
When the new expression was evaluated, it was negative. What is the least number of plus signs that Melanie could have changed to minus signs?