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a) \(\dfrac{\left(-3\right)^7\cdot2^8}{6^7}\)
\(=\dfrac{-1\cdot3^7\cdot2^8}{\left(2\cdot3\right)^7}=\dfrac{-1\cdot3^7\cdot2^7\cdot2}{2^7\cdot3^7}=-1\cdot2=-2\)
b) \(\dfrac{-3\cdot7^4+7^3}{7^5\cdot6-7^3\cdot2}\)
\(=\dfrac{-3\cdot7\cdot7^3+7^3}{7^3\cdot7^2\cdot6-7^3\cdot2}\)
\(=\dfrac{7^3\left(-3\cdot7+1\right)}{7^3\left(7^2\cdot6-2\right)}=\dfrac{-3\cdot7+1}{7^2\cdot6-2}\)
\(=\dfrac{-21+1}{294-2}=\dfrac{-20}{290}=\dfrac{-2}{29}\)
b) \(\dfrac{5^3\cdot3^5}{5^3\cdot0,5+125\cdot2\cdot5}\)
\(=\dfrac{5^3\cdot3^5}{5^3\cdot0,5+5^3\cdot2\cdot5}=\dfrac{5^3\cdot3^5}{5^3\left(0,5+2\cdot5\right)}\)
\(=\dfrac{3^5}{0,5+2\cdot5}=\dfrac{243}{10,5}=\dfrac{162}{7}\)
b) -3.7^4 + 7^3 / 7^5 . 6 - 7^3 .2
= -21 . 7^3 + 7^3 . 1 / 7^3 . 294 - 7^3 . 2
= 7^3 . (-21+1) / 7^3 . (294 - 2)
= 20/292 = 5/73
Tui Hông Hỉu, Dải Đáp Cho Tui Dới.............................
a) = 2(1-1/2+1/2-1/3+...+1/19-1/20)
= 2(1-1/20)
= 2.19/20
= 19/10
b) = 7(1/2-1/3+1/3-1/4+...+1/6-1/7)
= 7(1/2 - 1/7)
= 7.5/14
= 5/2
c) = 1/2-1/5+1/5-1/8+...+1/14-1/17
= 1/2 - 1/17
= 15/34
Chúc bạn học tốt nhé
a)2/1.2+2/2.3+....+2/19.20
=2(1/1.2+1/2.3+....+1/19.20)
=2(1-1/2+1/2-1/3+.....-1/20)
=2(1-1/20)
2(19/20)=38/20=19/10
b)7/2.3+7/3.4+7/4.5+7/5.6+7/6.7
7(1/2.3+1/3.4+1/4.5+1/5.6+1/6.7)
7(1/2-1/3+1/3-1/4+.....-1/7)
7(1/2-1/7)
7(7/14-2/14)=7.5/14=35/14=5/2
c)3/2.5+3/5.8+3/8.11+3/11.14+3/14.17
1/2-1/5+1/5-1/8+......+1/14-1/17
1/2-1/17=17/34-2/34=15/34
a) =-3/5 x (4/7 + 2/7 + 1) = -3/5 x 13/7 = -39/35
b) =8/11 x 5/19 + 7/19 x 8/11 - 8/11 x 1/15 = 8/11 x ( 5/19 + 7/19 - 1/15 ) = 8/11 x 161/285 = 1288/3235
**** cho mink nha
a, \(\frac{\left(\frac{1}{9}\right)^6\cdot\left(\frac{3}{8}\right)^7}{\left(\frac{1}{3}\right)^{13}\cdot\left(\frac{1}{2}\right)^{22}.3^6}\)
\(=\frac{\left(\frac{1}{\left(3^2\right)^6}\right)\cdot\left(\frac{1}{2}\cdot\frac{1}{2}\cdot\frac{1}{2}\cdot3\right)^7}{\left(\frac{1}{3}\right)^{13}.\left(\frac{1}{2}\right)^{22}.3^6}=\frac{\frac{1}{3^{12}}\cdot\left(\frac{1}{2}\right)^{21}\cdot3^7}{\frac{1}{3^{13}}\cdot\left(\frac{1}{2}\right)^{22}.3^6}\)
\(=\frac{3}{\frac{1}{3}\cdot\frac{1}{2}}=3\div\frac{1}{6}=3.6=18\)
b, Làm tương tự nha bn
ta có
\(-\frac{3^7\cdot2^8}{6^7}=-\frac{3^7\cdot2^7\cdot2}{6^7}=-\frac{6^7\cdot2}{6^7}=-2\)2
\(B=-\frac{3\cdot7^4+7^3}{7^5\cdot6-7^3\cdot2}=-\frac{3\cdot7^3\cdot7+7^3}{7^3\cdot7^2\cdot6-7^3\cdot2}=-\frac{7^3\cdot\left(3\cdot7+1\right)}{7^3\cdot\left(7^2\cdot6-2\right)}=-\frac{5}{73}\)