Toán Tính giá trị biểu thức 1/2 + 1/6 + 1/18 + 1/54 + 1/162 + 1/486 05/07/2021 By Piper Tính giá trị biểu thức 1/2 + 1/6 + 1/18 + 1/54 + 1/162 + 1/486
Đáp án: Giải thích các bước giải: Ta gọi: A = `1/2+1/6+1/18+1/54+1/162+1/486` 3A = `3/2+1/2+1/6+1/18+1/54+1/162` 3A-A=( `3/2+1/2+1/6+1/18+1/54+1/162`)-(`1/2+1/6+1/18+1/54+1/162+1/486`) 2A = `3/2-1/486` 2A =`364/243` A = `364/243`:2 A = `182/243` Trả lời
`1/2 + 1/6 + 1/18+ 1/54 + 1/162 + 1/486` = `243/486 + 81/486 + 27/486+ 9/486 + 3/486+ 1/486` `=\frac{243 + 81 + 27 + 9 + 3+1}{486}` `=364/486` `= 182/243` Trả lời
Đáp án:
Giải thích các bước giải:
Ta gọi: A = `1/2+1/6+1/18+1/54+1/162+1/486`
3A = `3/2+1/2+1/6+1/18+1/54+1/162`
3A-A=( `3/2+1/2+1/6+1/18+1/54+1/162`)-(`1/2+1/6+1/18+1/54+1/162+1/486`)
2A = `3/2-1/486`
2A =`364/243`
A = `364/243`:2
A = `182/243`
`1/2 + 1/6 + 1/18+ 1/54 + 1/162 + 1/486`
= `243/486 + 81/486 + 27/486+ 9/486 + 3/486+ 1/486`
`=\frac{243 + 81 + 27 + 9 + 3+1}{486}`
`=364/486`
`= 182/243`