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-49/81x27/(-77)
=-49x27/81x(-77)
=-1323/-6273
=1323/6273
=147/697
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-\dfrac{49}{81}.\dfrac{27}{-77}\)
\(=\dfrac{49.27}{81.77}\)
\(=\dfrac{7.7.27}{3.27.7.11}\)
\(=\dfrac{7}{3.11}\)
\(=\dfrac{7}{33}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 2 x 31 x 12 + 4 x 6 x 42 + 8 x 27 x 3
= 2 x 12 x 31 + 4 x 6 x 42 + 8 x 3 x 27
= 24 x 31 + 24 x 42 + 24 x 27
= 24 x ( 31 + 24 + 27 )
= 24 x 82
= 1968
b, 2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
= 24 x 53 + 24 x 87 - 24 x 40
= 24 x ( 53 + 87 - 40 )
= 24 x 100
= 2400
c, Tương tự
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(2.4.16.8=2.2^2.2^4.2^3=2^{1+2+4+3}=2^{10}\)
b) \(3^3.22^5.45=3^3.22^5.5.3^2=3^{3+2}.22^5=3^5.22^5=\left(3.22\right)^5=66^5\)
c) \(9.27.81=3^2.3^3.3^4=3^{2+3+4}=3^9\)
d) \(36.30.125=6^2.5.6.5^3=6^{2+1}.5^{3+1}=6^3.5^4\)
e) \(2.4.8.16.256=2.2^2.2^3.2^4.2^8=2^{1+2+3+4+8}=2^{18}\)
g) \(3.9.27.81.729=3.3^2.3^3.3^4.3^6=3^{1+2+3+4+6}=3^{16}\)
h) \(5.25.125.625.75=5.5^2.5^3.5^4.5^2.3=5^{1+2+3+4+2}.3=5^{12}.3\)
k) \(7.49.343.77=7.7^2.7^3.7.11=7^{1+2+3+1}.11=7^7.11\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1) $(-81)\cdot27-3^4\cdot(-77)$
$=(-81)\cdot27-81\cdot(-77)$
$=-81\cdot[27+(-77)]$
$=-81\cdot(27-77)$
$=-81\cdot(-50)$
$=81\cdot50$
$=4050$
2) $(-16)\cdot32-(-4)^2\cdot18$
$=(-16)\cdot32-16\cdot18$
$=-16\cdot(32+18)$
$=-16\cdot50$
$=-800$
3) $(-2)^4\cdot289-16\cdot189$
$=16\cdot289+16\cdot(-189)$
$=16\cdot[289+(-189)]$
$=16\cdot(289-189)$
$=16\cdot100$
$=1600$
4) $41\cdot(-18)+41\cdot(-81)-41$
$=1\cdot(-18)+41\cdot(-81)+41\cdot(-1)$
$=41\cdot[(-18)+(-81)+(-1)]$
$=41\cdot(-18-81-1)$
$=41\cdot(-99-1)$
$=41\cdot(-100)$
$=-4100$
5) $17\cdot(-37)-23\cdot37-46\cdot(-37)$
$=17\cdot(-37)+23\cdot(-37)-46\cdot(-37)$
$=-37\cdot(17+23-46)$
$=-37\cdot(40-46)$
$=-37\cdot(-6)$
$=37\cdot6$
$=222$
6) $-48+48\cdot(-78)+48\cdot(-21)$
$=48\cdot(-1)+48\cdot(-78)+48\cdot(-21)$
$=48\cdot[(-1)+(-78)+(-21)]$
$=48\cdot(-1-78-21)$
$=48\cdot(-79-21)$
$=48\cdot(-100)$
$=-4800$
7) $29\cdot(-13)+27\cdot(-29)+(-14)\cdot(-29)$
$=-29\cdot13+27\cdot(-29)+(-14)\cdot(-29)$
$=-29\cdot[13+27+(-14)]$
$=-29\cdot(40-14)$
$=-29\cdot26$
$=-754$
$\text{#}Toru$
![](https://rs.olm.vn/images/avt/0.png?1311)
49 x 77 - 302 + 23 x 49
=49x(77+23)-302
=49x100-900
=4900-900
=4000
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
Bài 2: Tính\(\frac{1-3-5-7-...-49}{89}=\frac{1-\left(3+5+7+9+...+49\right)}{89}=\frac{1-\left(\left(49+3\right)\times\left(\frac{49-3}{2}+1\right)\div2\right)}{89}=\frac{1-\left(52\times24\div2\right)}{89}=\frac{1-624}{89}=\frac{-623}{89}=-7\)
k cho mình nha Đô Mỹ Diệu Linh
1)
\(\frac{\left(-3\right)^x}{81}=-27\)
\(\left(-3\right)^x=-27.81=-2187\)
\(\left(-3\right)^x=\left(-3\right)^7\)
\(=>x=7\)
\(\dfrac{-49}{81}\cdot\dfrac{27}{-77}\)
\(=\dfrac{-7^2}{3^2\cdot9}\cdot\dfrac{3\cdot9}{-7\cdot11}\)
\(=\dfrac{7}{3\cdot11}\)
\(=\dfrac{7}{33}\)