Question 146
Determine, with proof, the value of
$$
1^{2}-2^{2}+3^{2}-4^{2}+5^{2}-\cdots+97^{2}-98^{2}+99^{2} .
$$
$$
1^{2}-2^{2}+3^{2}-4^{2}+5^{2}-\cdots+97^{2}-98^{2}+99^{2} .
$$
MathNet 2026 — Part 10 Question 146
Math Olympiad Vault · MathNet 2026 — Part 10