Đáp án: `= 17/36` Giải thích các bước giải: `1/4+1/16+1/36+1/64 +……+1/324 ` `= 1/4 . (1 + 1/4 + 1/9 + 1/16 + …. + 1/81)` `= 1/4 . ( 1 + (1/2)^2 + (1/3)^2 + …. + (1/9)^2 )` `= 1/4 . 17/9` `= 17/36` Bình luận
TL: $\frac{1}{4}$ $+\frac{1}{16}$ $+\frac{1}{36}$ $+\frac{1}{64}$ $+…+\frac{1}{324}$ $=\frac{1}{4}$ $( 1 + \frac{1}{2^2}$ $+\frac{1}{4^2}$ $+…+\frac{1}{9^2})$ $=\frac{1}{1.2}$ $+\frac{1}{2.3}$ $+\frac{1}{3.4}$ $+…+\frac{1}{7.8}$ $\frac{1}{8.9}$ $=\frac{1}{4}$ $.\frac{17}{9}$ $=\frac{17}{36}$ Bình luận
Đáp án: `= 17/36`
Giải thích các bước giải:
`1/4+1/16+1/36+1/64 +……+1/324 `
`= 1/4 . (1 + 1/4 + 1/9 + 1/16 + …. + 1/81)`
`= 1/4 . ( 1 + (1/2)^2 + (1/3)^2 + …. + (1/9)^2 )`
`= 1/4 . 17/9`
`= 17/36`
TL:
$\frac{1}{4}$ $+\frac{1}{16}$ $+\frac{1}{36}$ $+\frac{1}{64}$ $+…+\frac{1}{324}$
$=\frac{1}{4}$ $( 1 + \frac{1}{2^2}$ $+\frac{1}{4^2}$ $+…+\frac{1}{9^2})$
$=\frac{1}{1.2}$ $+\frac{1}{2.3}$ $+\frac{1}{3.4}$ $+…+\frac{1}{7.8}$ $\frac{1}{8.9}$
$=\frac{1}{4}$ $.\frac{17}{9}$ $=\frac{17}{36}$