\(2^3-5^3:5^2+12\cdot2^2=8-5+48=51\\ 5\left[\left(85-35:7\right):8+90\right]-5\cdot2^2\\ =5\left(80:8+90\right)-20=5\cdot100-20=480\)

2 . [ { 7 -3 mũ 3 : 3 mũ 2 } : 2 mũ 2 + 99 ] - 100

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

\(5^{12}.7-5^{11}.10\)

\(=5^{11}.\left(5.7-10\right)\)

\(=5^{11}.25\)

\(=5^{11}.5^2\)

\(=5^{13}\)

\(2^{20}.15+2^{20}.85\)

\(=2^{20}.5\left(3+17\right)\)

\(=2^{20}.100\)

\(=104857600\)

\(125^3:25^4\)

\(=\left(5^3\right)^3:\left(5^2\right)^4\)

\(=5^9:5^8\)

\(=5\)

\(24^4:3^4-32^{12}:16^{12}\)

\(=\left(24:3\right)^4-\left(32:16\right)^{12}\)

\(=8^4-2^{12}\)

\(=0\)

( 5 . 2 mũ 2 - 20 ) : 5

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 ....

A = 4 + 4⁴ + 4⁷  + ... + 4³¹ 

4³A = 4³.(4 + 4⁴ + 4⁷ + ... + 4³¹) 

64A = 4⁴ + 4⁷ + 4¹⁰ + ... + 4³⁴ 

64A - A = (4⁴ + 4⁷ + ... + 4³⁴) - (4 + 4⁴ + ... + 4³¹) 

63A = 4³⁴ - 4 

=> A = \(\frac{4^{34}-4}{63}\)

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: \(=\dfrac{5^3\cdot3^6\cdot5^4\cdot2^8\cdot3^{16}\cdot2^2}{\left(2^2\cdot3^2\cdot5\right)^5}=\dfrac{5^{10}\cdot3^{22}\cdot2^{10}}{2^{10}\cdot3^{10}\cdot5^5}=3^{12}\cdot5^5\)

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

đợi xíu nhé tí nữ mình trả lời cho bh mình đanbg bận