Cho A= $\frac{4}{2015}$×(3×$\frac{2011}{2013}$+$\frac{1}{2015}$× $\frac{2}{2013}$- $\frac{6033}{2013 ×2015}$
Đặt a= $\frac{1}{2015}$, b= $\frac{2011}{2013}$
a, Rút gọn A
b, Tính giá trị $\frac{1}{A}$
Cho A= $\frac{4}{2015}$×(3×$\frac{2011}{2013}$+$\frac{1}{2015}$× $\frac{2}{2013}$- $\frac{6033}{2013 ×2015}$ Đặt a= $\frac{1}{2015}$, b= $\frac{2011}
By Liliana
a)
`A = 4. 1/2015 . (3 . 2011/2013 + 2/(2013.2015) – 6033/(2013 . 2015)`
`A = 4a . (3b + a . 2/2013 – 3ab)`
`= 12ab + (8a^2)/2013 – 12a^2b`
`= 12 . 1/2015 . 2011/2013 + 8 . 1/(2015^2) : 2013 – 12 . (1/2015)^2 . 2011/2013`
`= 1/155`
b) `1/A = 155`
Đừng để ý “D“
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