Đáp án:
$\\$
`b,`
`(2^{18} - 2^8)/(2^{20} - 2^5)`
`= (2^5 (2^{13} - 2^3) )/(2^5 (2^{15} - 1) )`
`= (2^{13} - 2^3)/(2^{15}-1)`
`= (8192 - 8)/(32768-1)`
`= 8184/32767`
`= 264/1057`
$\\$
`d,`
`(3^7 - 3^4)/(27 × 10^2 + 27 ×5^2 + 135)`
`= (3^7 - 3^4)/(3^3 × 10^2 + 3^3 ×5^2 + 3^3×5)`
`= (3^3 (3^4 - 3) )/(3^3 (10^2 + 5^2 + 5) )`
`= (3^4-3)/(10^2 + 5^2+5)`
`= (81 -3)/(100 + 25+5)`
`= 78/(125+5)`
`= 78/130`
`= 3/5`
