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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) \(2^5:8^4=2^5:\left(2^3\right)^4=2^5:2^{12}=2^{-7}=\frac{1}{2^7}\)\(=\left(\frac{1}{2}\right)^7\)
b) \(25^6:125^3=\left(5^2\right)^6:\left(5^3\right)^3=5^{12}:5^9=5^3\)
c) \(625^2:25^7=\left(5^4\right)^2:\left(5^2\right)^7=5^8:5^{14}=5^{-6}=\frac{1}{5^6}=\left(\frac{1}{5}\right)^6\)
d) \(12^3.3^3=\left(12.3\right)^3=36^3\)
e) \(32^2:2^4=\left(2^5\right)^2:2^4=2^{10}:2^4=2^6\)
g) \(64.2:2^5=2^6.2:2^5=2^7:2^5=2^2\)
Mk làm hộ bn rùi đó nhớ ủng hộ mk nha ^_^
a) (1 phần 2 ) mũ 7
b) 5 mũ 3
c) (1 phần 5 ) mũ 6
d) 36 mũ 3
e) 2 mũ 6
g) 2 mũ 2
1. 2x=16\(\Rightarrow\)X=4
2. 22x-1=27
\(\Rightarrow\)27=22.4-1
Vậy x =4
b>
2 mũ 56 nhân 125 mũ 7 = 3,435973837* 10 mủ 31
c>
625 mũ 5 nhân 25 mũ7 = 5,920766091* 10 mủ 23
d>
12 mũ 3 nhân 3 mũ 3 =10077606
e>
24 mũ 4 chia 3 mũ 4 - 32 mũ 12 nhân 16 mũ 12 = -2,882303762 * 10 mủ 17
g>
( 5 mũ 3 + 5 mũ 4 +125 mũ 2) chia 5 mũ 3= 131
Ta đặt : \(A=1^2+2^2+3^2+...+12^2=625\)
\(\Rightarrow2A=2^2+4^2+6^2+...+24^2\)
\(\Leftrightarrow2A=1250\)
Vì \(1^2+2^2+3^2+......+12^2=625\)
\(\Rightarrow2^2+4^2+6^2+.......+24^2\)
\(=\left(1.2\right)^2+\left(2.2\right)^2+\left(3.2\right)^2+........+\left(12.2\right)^2\)
\(=1^2.2^2+2^2.2^2+3^2.2^2+.....+12^2.2^2\)
\(=1^2.4+2^2.4+3^2.4+......+12^2.4\)
\(=4.\left(1^2+2^2+3^2+.......+12^2\right)\)
\(=4.625=2500\)