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1: Ta có: \(\left(7x-3^2\right):5=8\)
\(\Leftrightarrow7x-9=40\)
hay x=7
b: \(5\cdot\left[\left(85-35:7\right):8+90\right]-5^2\cdot2\)
\(=5\cdot\left[\left(85-5\right):8+90\right]-25\cdot2\)
\(=5\cdot\left(10+90\right)-50\)
=450
Giải: (^ là mũ)
a) 3^8 : 3^4 + 2^2 . 2^3
= 6561 : 81 + 4 . 8
= 81 + 32
= 113
Mấy câu sau bn làm tương tự nhé!
b: \(=2^{12}\cdot3^4\cdot\dfrac{3^{10}}{3^{12}\cdot2^{12}}=3^2=9\)
c: \(=\dfrac{7^2\cdot3^2\cdot7\cdot2\cdot5^3}{5^3\cdot7^3\cdot2\cdot3}=\dfrac{3^2}{3}=3\)
d: \(=\dfrac{5^3\cdot3^6\cdot5^4\cdot2^8\cdot3^{16}\cdot2^2}{\left(2^2\cdot3^2\cdot5\right)^5}=\dfrac{5^{10}\cdot3^{22}\cdot2^{10}}{2^{10}\cdot3^{10}\cdot5^5}=3^{12}\cdot5^5\)
\(2^3-5^3:5^2+12\cdot2^2=8-5+48=51\\ 5\left[\left(85-35:7\right):8+90\right]-5\cdot2^2\\ =5\left(80:8+90\right)-20=5\cdot100-20=480\)
Thế này à:
a, \(\frac{2^{13}+25}{2^{10}}\)
b, \(\frac{21^2.14.125}{35^5.6}\)
c,\(\frac{45^3.20^4.18^2}{180^5}\)
d, \(\frac{11.3^{22}.3^7-9^{15}}{\left(2.3^{14}\right)^2}\)
2 mũ 13 ta chia cho 2 mũ 10 ta có là 2 mũ 3 chuyển thành 8 rồi cộng cho 25 ta có là 33
85+(-35)+(-12)+(-35)=50+(-12)+(-35)=38+(-35)=3
53.42+85.53-57:54=125.16+85.125-53=125.16+85.125-125
=125.16+85.125-125.1=(16+85-1).125=100.125=12500
a) 38 : 34 + 22 x 23 = 113
b) 3 x 42 - 2 . 3 = 42
c) 46 . 34 . 95 : 612 = 9
d) 212 . 14 . 125 : 353 . 6 = 108
e) 453 . 204 .182 : 1805 = 25
#BạcHà#
bn ơi ghi cả cách làm nữa bn
ai lm lun cách làm mk sẽ k cho 2 k lun
a, \(390-\left(x-7\right)=13^2:12\)
\(390-\left(x-7\right)=\) \(\dfrac{169}{12}\)
\(x-7=390-\dfrac{169}{12}\)
\(x-7=\dfrac{4511}{12}\)
\(x=\dfrac{4511}{12}+7\)
\(x=\dfrac{4595}{12}\)
Vậy ...
b, \(\left(x-35.2^2\right):7=3^3-24\)
\(\left(x-35.4\right):7=27-24\)
\(\left(x-140\right):7=3\)
\(\Leftrightarrow\left(x-140\right)=3.7\)
\(\Leftrightarrow x-140=21\)
\(\Leftrightarrow x=161\)
Vậy .....
c) \(x-6:2-\left(4^2.3-24\right):2:6=3\)
\(x-3-\left(16.3-24\right):2:6=3\)
\(x-3-\left(48-24\right):2:6=3\)
\(x-3-24:2:6=3\)
\(x-3-2=3\)
\(x=3+2+3\)
\(x=8\)
Vậy ......
d) \(4x-5=5+5^2+5^3+.....+5^{99}\)
Đặt :
\(A=5+5^2+.........+5^{99}\)
\(\Leftrightarrow5A=5^2+5^3+..........+5^{100}\)
\(\Leftrightarrow5A-A=\left(5^2+5^3+......+5^{100}\right)-\left(5+5^2+....+5^{99}\right)\)
\(\Leftrightarrow4A=5^{100}-5\)
\(\Leftrightarrow A=\dfrac{5^{100}-5}{4}\)
\(\Leftrightarrow4x+5=\dfrac{5^{100}-5}{4}\)
Đến đây thì sao nữa nhỉ ?
e) \(\left(2x-1\right)^4=625\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(2x-1\right)^4=5\\\left(2x-1\right)^4=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
Vậy ....
1) (5+54)+(52+55)+...........+(52003+52006)= 5(1+53)+52(1+53)+..............+52003(1+53)
= (5+52+..........+52003).126 ->S chia hết cho 126
2, 7+73+................+71997+71999 = 7(1+72)+..............+71997(1+72)
= (7+...............+71997).50-> chia hết cho 5
= 7(1+72+.......+71998) -> chia hết cho 7
-> chia hết cho 35