Câu hỏi 18
Cho $f(x)=\cos^2(\pi x/2)$. Tính
$$f\left(\frac1{2023}\right)+f\left(\frac2{2023}\right)+\cdots+f\left(\frac{2021}{2023}\right)+f\left(\frac{2022}{2023}\right).$$
$$f\left(\frac1{2023}\right)+f\left(\frac2{2023}\right)+\cdots+f\left(\frac{2021}{2023}\right)+f\left(\frac{2022}{2023}\right).$$