Đáp án:

Giải thích các bước giải:

` C = ( 1 - 1/2 ) xx ( 1 + 1/2 ) xx ( 1 - 1/3 ) xx ( 1 1/3 ) xx ........ xx ( 1 - 1/2025 ) xx ( 1 + 1/2025 ) `

` C = 1/2 xx 3/2 xx 2/3 xx 4/3 xx ....... xx 2024/2025 xx 2026/2025 `

` C = ( 1/2 xx 2/3 xx 3/4 xx ...... xx 2024/2025 ) xx ( 3/2 xx 4/3 xx ..... xx 2026/2025 ) `

` C = ( (1 xx 2 xx 3 xx ....... xx 2024)/(2 xx 3 xx 4 xx ...... xx 2025) ) xx ( (3 xx 4 xx ....... 2026)/(2 xx 3 xx ..... xx 2025) ) `

` C = 1/2025 xx 2026/2 `

` C = 2013/2025`