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\(A=15^{28}=(15^2)^{14}=225^{14}\)
\(B=6^{42}=(6^3)^{14}=216^{14}\)
Mà \(225>216\)nên \(15^{28}>6^{42}\)hoặc \(A>B\)
Mình chỉ làm tạm thôi nha bạn
![](https://rs.olm.vn/images/avt/0.png?1311)
\(703-140:\left(42+28\right)-17^{15}:17^{13}\)
\(=730-140:70-17^2\)
\(=730-2-289\)
\(=439\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{11}{13}-\left(\frac{5}{42}-x\right)=-\left(\frac{15}{28}-\frac{11}{13}\right)\)
\(=\frac{11}{13}-\left(\frac{5}{42}-x\right)=\frac{113}{364}\)
\(\Rightarrow\frac{5}{42}-x=\frac{11}{13}-\frac{113}{364}\)
\(\Rightarrow x=\frac{5}{42}-\frac{15}{28}\)
\(\Rightarrow x=\frac{-5}{12}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{1}{13}-\left(\frac{5}{42}-x\right)=-\left(-\frac{113}{364}\right)\)
=>\(\frac{1}{13}-\frac{5}{42}+x=\frac{113}{364}\)
=>\(-\frac{23}{546}+x=\frac{113}{364}\)
=>\(x=\frac{113}{364}-\left(-\frac{23}{546}\right)\)
=>\(x=\frac{113}{364}+\frac{23}{546}\)
=>\(x=\frac{55}{156}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(15^{28}=\left(15^2\right)^{14}=225^{14}\)
\(6^{42}=\left(6^3\right)^{14}=216^{14}\)
\(225>216\Rightarrow225^{14}>216^{14}\Rightarrow15^{28}>6^{42}\)
1528 và 642
Ta có :
1528 = ( 152 )14 = 22514
642 = ( 63 )14 = 21614
Vì 22514 > 21614 ( 225 > 216 )
Nên 1528 > 642
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(\dfrac{-10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)
=\(\dfrac{10}{11}.\dfrac{-8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)
=\(\dfrac{10}{11}(\dfrac{-8}{9}+\dfrac{7}{18})\)
=\(\dfrac{10}{11}.\dfrac{-1}{2}\)
=\(\dfrac{-5}{11}\)
b;
B = \(\dfrac{3}{14}\) : \(\dfrac{1}{28}\) - \(\dfrac{13}{21}\): \(\dfrac{1}{28}\) + \(\dfrac{29}{42}\) : \(\dfrac{1}{28}\) - 8
B = (\(\dfrac{3}{14}\) - \(\dfrac{13}{21}\) + \(\dfrac{29}{42}\)) - 8
B = (\(\dfrac{9}{42}\) - \(\dfrac{26}{42}\) + \(\dfrac{29}{42}\)) - 8
B = (\(\dfrac{-17}{42}\) + \(\dfrac{29}{42}\)) - 8
B = \(\dfrac{2}{7}\) - 8
B = \(\dfrac{2}{7}-\dfrac{56}{7}\)
B = - \(\dfrac{54}{7}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
A) 25 - 15 : x = 20
15 : x = 25 - 20
15 : x = 5
x = 15 : 5
x = 3
B) x - [ 42 + ( - 28 ) ] = -8
x - 14 = - 8
x = ( - 8 ) + 14
x = 6
chúc bn hok tốt @_@
A) 25 - 15 : x = 20
15 : x = 25 - 20
15 : x = 5
x = 15 : 5
x = 3
B) x - [ 42 + ( - 28 ) ] = -8
x - 14 = - 8
x = ( - 8 ) + 14
x = 6
=1500 nha bạn! ^.^ -.- ?
hok tốt nhé !^o^
\(42.15-28.15+86.15\)
= \(\left(42-28+86\right).15\)
= \(100.15\)
= \(1500\)
Chúc bạn học tốt !!!