a.3/2 +3/8+3/32+3/128+3/512 b.3+3/5+3/25=3/125+3/625 ko làm tắt nha 19/08/2021 Bởi Elliana a.3/2 +3/8+3/32+3/128+3/512 b.3+3/5+3/25=3/125+3/625 ko làm tắt nha
$a$. Đặt `A = 3/2 +3/8+3/32+3/128+3/512` `⇔ 4A = 6 + 3/2 + 3/8 + 3/{32} + 3/{128}` `⇔ 4A – A = (6 + 3/2 + 3/8 + 3/{32} + 3/{128})-(3/2 +3/8+3/32+3/128+3/512)` `⇔ 3A = 6 – \frac{3}{512}` `⇔ A = {1023}/{512}` $⇒$ `3/2 +3/8+3/32+3/128+3/512= {1023}/{512}` $b$) Đặt `B = 3+3/5+3/25+3/125+3/625` `⇔ 5B = 15 + 3 + 3/{5} + 3/{25} + 3/{125}` `⇔ 5B – B = (15 + 3 + 3/{5} + 3/{25} + 3/{125})-(3+3/5+3/25+3/125+3/625)` `⇔ 4B= 15 -\frac{3}{625}` `⇔ B = {2343}/{625}` $⇒$ `3+3/5+3/25+3/125+3/625={2343}/{625}` Bình luận
Đáp án : a, Đặt A = $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ + $\frac{3}{512}$ ⇔ 4A = 6 + $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ ⇔ 4A – A = ( 6 + $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ ) – ( $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ + $\frac{3}{512}$ ) ⇔ 3A = 6 – $\frac{3}{512}$ ⇔ A = $\frac{1 023}{512}$ ⇒ $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ + $\frac{3}{512}$ = $\frac{1 023}{512}$ b, Đặt B = 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ + $\frac{3}{625}$ ⇔ 5B = 15 + 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ ⇔ 5B – B = ( 15 + 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ ) – ( 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ + $\frac{3}{625}$ ) ⇔ 4B = 15 – $\frac{3}{625}$ ⇔ B = $\frac{2 343}{625}$ ⇒ 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ + $\frac{3}{625}$ = $\frac{2 343}{625}$ No copy . Chúc bạn học tốt . Cho mink ctlhn nha . Knock Down Anybody . Bình luận
$a$. Đặt `A = 3/2 +3/8+3/32+3/128+3/512`
`⇔ 4A = 6 + 3/2 + 3/8 + 3/{32} + 3/{128}`
`⇔ 4A – A = (6 + 3/2 + 3/8 + 3/{32} + 3/{128})-(3/2 +3/8+3/32+3/128+3/512)`
`⇔ 3A = 6 – \frac{3}{512}`
`⇔ A = {1023}/{512}`
$⇒$ `3/2 +3/8+3/32+3/128+3/512= {1023}/{512}`
$b$) Đặt `B = 3+3/5+3/25+3/125+3/625`
`⇔ 5B = 15 + 3 + 3/{5} + 3/{25} + 3/{125}`
`⇔ 5B – B = (15 + 3 + 3/{5} + 3/{25} + 3/{125})-(3+3/5+3/25+3/125+3/625)`
`⇔ 4B= 15 -\frac{3}{625}`
`⇔ B = {2343}/{625}`
$⇒$ `3+3/5+3/25+3/125+3/625={2343}/{625}`
Đáp án :
a,
Đặt A = $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ + $\frac{3}{512}$
⇔ 4A = 6 + $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$
⇔ 4A – A = ( 6 + $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ )
– ( $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ + $\frac{3}{512}$ )
⇔ 3A = 6 – $\frac{3}{512}$
⇔ A = $\frac{1 023}{512}$
⇒ $\frac{3}{2}$ + $\frac{3}{8}$ + $\frac{3}{32}$ + $\frac{3}{128}$ + $\frac{3}{512}$ = $\frac{1 023}{512}$
b,
Đặt B = 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ + $\frac{3}{625}$
⇔ 5B = 15 + 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$
⇔ 5B – B = ( 15 + 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ )
– ( 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ + $\frac{3}{625}$ )
⇔ 4B = 15 – $\frac{3}{625}$
⇔ B = $\frac{2 343}{625}$
⇒ 3 + $\frac{3}{5}$ + $\frac{3}{25}$ + $\frac{3}{125}$ + $\frac{3}{625}$ = $\frac{2 343}{625}$
No copy .
Chúc bạn học tốt .
Cho mink ctlhn nha .
Knock Down Anybody .