Trang chủ » Hỏi đáp » Môn Toán Tính 5/5×8 + 5/8×11+…+5/92×95 24/10/2023 Tính 5/5×8 + 5/8×11+…+5/92×95
5/(5xx8)+5/(8xx11)+…+5/(92xx95) =1/3xx(5/5-5/8)+1/3xx(5/8-5/11)+……+1/3xx(5/92-5/95) =1/3xx(5/5-5/8+5/8-5/11+….+5/92-5/95) =1/3xx(5/5-5/95) =1/3xx18/19 =6/19 Trả lời
Đặt B=5/(5.8)+5/(8.11)+…+5/(92.95) => 3/5 B=3/(5.8)+3/(8.11)+…+3/(92.95) => 3/5 B=1/5-1/8+1/8-1/11+…+1/92-1/95 => 3/5 B=1/5-1/95 => 3/5 B=18/95 => B=6/19 Trả lời
