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2x - 3 = 54 : 52
2x - 3 = 54 - 2 = 52 = 25
2x = 25 + 3
2x = 28
x = 28 : 2
x = 14
5x + 2 = 53 . 125
5x + 2 = 53 . 53 = 53 + 3 = 56
=> x = 6 - 2
x = 4
a) \(125^3:25^4=\left(5^3\right)^3:\left(5^2\right)^4=5^9:5^8=5\)
b) \(\left(10^3+10^4+125^2\right):5^3\)
\(=\left[\left(5.2\right)^3+\left(5.2\right)^4+\left(5^3\right)^2\right]:5^3\)
\(=\left(5^3.2^3+5^4.2^4+5^6\right):5^3\)
\(=\frac{5^3.2^3}{5^3}+\frac{5^4.2^4}{5^3}+\frac{5^6}{5^3}\)
\(=2^3+5.2^4+5^3=213\)
c) \(24^4:3^4-32^{12}:16^{12}\)
\(=\left(3.8\right)^4:3^4-\left(16.2\right)^{12}:16^{12}\)
\(=3^4.8^4:3^4-2^{12}.16^{12}:16^{12}\)
\(=8^4-2^{12}=\left(2^3\right)^4-2^{12}=2^{12}-2^{12}=0\)
a) \(\left(2x+1\right)^2=81\)
\(\Rightarrow\left(2x+1\right)^2=9^2\)
\(\Rightarrow2x+1=9\)
\(\Rightarrow2x=9-1=8\)
\(\Rightarrow x=8:2=4\)
\(\Rightarrow x=4\)
b)\(\left(3-x\right)^4=1\)
\(\Rightarrow\left(3-x\right)^4=1^4\)
\(\Rightarrow3-x=1\)
\(\Rightarrow x=3-1=2\)
\(\Rightarrow x=2\)
c) \(\left(x+4\right)^3=125\)
\(\Rightarrow\left(x+4\right)^3=5^3\)
\(\Rightarrow x+4=5\)
\(\Rightarrow x=5-4=1\)
\(\Rightarrow x=1\)
k mk nha. CHÚC BẠN HỌC TỐT. ^_^
B1:
Ta có: \(\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}=\frac{2^{12}.3^{10}-2^9.3^9.2^3.3.5}{2^{12}.3^{12}-2^{11}.3^{11}}\)
\(=\frac{2^{12}.3^{10}-2^{12}.3^{10}.5}{2^{12}.3^{12}-2^{11}.3^{11}}=\frac{2^{12}.3^{10}.\left(1-5\right)}{2^{11}.3^{11}.\left(2.3-1\right)}\)
\(=\frac{2.\left(-4\right)}{3.5}=-\frac{8}{15}\)
B2:
Ta có: \(1+3+5+...+x=1600\)
\(\Leftrightarrow\frac{\left(x+1\right)\cdot\left(\frac{x-1}{2}+1\right)}{2}=1600\)
\(\Leftrightarrow\left(x+1\right)\cdot\frac{x+1}{2}=3200\)
\(\Leftrightarrow\left(x+1\right)^2=6400\)
Xét theo dãy tăng tiến ta thấy được giá trị của x càng tăng
=> x dương => x + 1 dương
\(\Rightarrow x+1=80\)
\(\Rightarrow x=79\)
mời bạn đừng thi thì tốt hơn 
a.1253:254= 1253= ( 53)4=53.4=512
254=(52)4=52.5=510
\(\Rightarrow\)512>510
\(\Rightarrow\)1253>254
k mik nhé