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A=1-1/2+1/2-1/4+1/4-1/8+1/8-1/16+1/16-1/32+1/32-1/64
A=1- bạn gạch chéo từ 1/2(đầu tiên) đến 1/32 nha
A=1-1/64=65/64.
B=Bạn làm tương tự như trên nha
k mik nha. Thanks. Chúc bạn học tốt!!!
a) A=1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64
2A=1+1/2+1/4 + 1/8 + 1/16 + 1/32
2A-A= 1+1/2+1/4+1/8+1/16+1/32-(1/2+1/4+1/8+1/16+1/32+1/64)
A= 1-1/64=63/64
b) B= 1/4+1/8+1/16+......+1/512
2B= 1/2+1/4+1/8+1/16+......+1/256
2B-B=1/2+1/4+1/8+1/16+.....+1/256-(1/4+1/8+1/16+.....+1/512)
B=1/2-1/512=255/512
Tham khảo câu hỏi tương tự tại đây: https://olm.vn/hoi-dap/detail/54687769377.html
9+3+2+1+7+8+5+10+6+4= (9+1)+(2+8)+(3+7)+(4+6)+5=10+10+10+10+5=10.4+5=40+5=45
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12
= ( 1 + 12 ) + ( 2 + 11 ) + ( 3 + 10 ) + ( 4 + 9 ) + ( 5 + 8 ) + ( 6 + 7 )
= 13 + 13 + 13 + 13 + 13 + 13
= 13 x 6
= 78
sai thui
C1 : 3/4 x 1/2 x 2
= 3/8 x 2
= 3/4
C2 : 3/4 x 1/2 x 2
= 3/4 x ( 1/2 x 2 )
= 3/4 x 1
= 3/4
\(\frac{5}{2}\)x\(\frac{1}{3}\)+\(\frac{1}{4}\)= \(\frac{5}{6}\)+\(\frac{1}{4}\)= \(\frac{10}{12}\)+\(\frac{3}{12}\)= \(\frac{13}{12}\)
\(\frac{5}{2}\)-\(\frac{1}{3}\):\(\frac{1}{4}\)= \(\frac{5}{2}\)-\(\frac{1}{3}\)x\(\frac{4}{1}\)= \(\frac{5}{2}\)-\(\frac{4}{3}\)= \(\frac{15}{6}\)-\(\frac{8}{6}\)=\(\frac{7}{6}\)
Chi tiết lun nha, nhớ k đúng cho mik nha :33
\(\frac{5}{2}\times\frac{1}{3}+\frac{1}{4}\)
\(=\frac{5}{6}+\frac{1}{4}\)
\(=\frac{10}{12}+\frac{3}{12}\)
\(=\frac{13}{12}\)
\(\frac{5}{2}-\frac{1}{3}\div\frac{1}{4}\)
\(=\frac{5}{2}-\frac{1}{3}\times\frac{4}{1}\)
\(=\frac{5}{2}-\frac{4}{3}\)
\(=\frac{15}{6}-\frac{8}{6}\)
\(=\frac{7}{6}\)
\(\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot...\cdot\left(1-\frac{1}{99}\right)\cdot\left(1-\frac{1}{100}\right)\)
\(=\frac{1}{2^{\left(1\right)}}\cdot\frac{2^{\left(1\right)}}{3^{\left(1\right)}}\cdot\frac{3^{\left(1\right)}}{4^{\left(1\right)}}\cdot...\cdot\frac{98^{\left(1\right)}}{99^{\left(1\right)}}\cdot\frac{99^{\left(1\right)}}{100}\)
\(=\frac{1}{100}\)
Đặt A = 1/2 + 1/4 + 1/8 + 1/16 + ... + 1/2048
2A = 1 + 1/2 + 1/4 + 1/8 + ... + 1/1024
2A - A = 1 + 1/2 + 1/4 + 1/8 + ... + 1/1024 - 1/2 - 1/4 - 1/8 - 1/16 - ... . 1/2048
A = 1 - 1/ 2048
A = 2047 / 2048
Vậy 1/2+ 1/4 + 1/8 + 1/16 + ... + 1/2048 = 2047/2048