tìm x: 105-[(2x+7)-13]=( -15) mũ 10: ( 9 mũ 5. 5 mũ 8)
giải giúp mik nhé, đang cần rất gấp
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\(105-\left[\left(2x+7\right)-13\right]=\left(-15\right)^{10}:\left(9^5.5^8\right)\\ 105-\left[\left(2x+7\right)-13\right]=25\\ \left(2x+7\right)-13=105-25\\ \left(2x+7\right)-13=80\\ 2x+7=80+13\\ 2x+7=93\\ 2x=93-7\\ 2x=86\\ x=\dfrac{86}{2}\\ x=43\)
\(105-\left[\left(2x+7\right)-13\right]=\left(-15\right)^{10}:\left(9^5.5^8\right)\\ 105-\left[\left(2x+7\right)-13\right]=15^{10}:3^{10}:5^8\\ 105-\left[\left(2x+7\right)-13\right]=5^{10}:5^8\\ 105-\left[\left(2x+7\right)-13\right]=25\\ \left(2x+7\right)-13=105-25\\ \left(2x+7\right)-13=80\\ 2x+7=80+13\\ 2x+7=93\\ 2x=93-7\\ 2x=86\\ x=86:2\\ x=43\)
\(b,\left(2\chi-7\right)^{4-1}=4^{2\times5}\)\(a,3\times2^{\chi-7}=17\)
a) \(3.2^x-7=17\)
\(3\cdot2^x=24\)
\(2^x=8=2^3\)
=> x = 3
b) \(\left(2x-7\right)^4-1=4^2\cdot5\)
\(\left(2x-7\right)^4-1=80\)
\(\left(2x-7\right)^4=81=\left(\pm3\right)^4\)
+) 2x - 7 = 3
2x = 10
x = 5
+) 2x - 7 = -3
2x = 4
x = 2
Vậy,...........
Câu 1:
\(8^3 . 8^9 . 8^{27} . ... . 8^{729} . 8^{2187}\)
\(=8^{3+9+27+...+729+2187}\)
\(=8^{3279}\)
Câu 2:
\((3^{50}+3^{51}+3^{52}):3^{49}\)
\(=3^{50}:3^{49}+3^{51}:3^{49}+3^{52}:3^{49}\)
\(=3+3^2+3^3\)
\(=3+9+27\)
\(=39\)
Câu 3:
\((5^{2015}+5^{2013}):5^{2013}\)
\(=5^{2015}:5^{2013}+5^{2013}:5^{2013}\)
\(=5^2+1\)
\(=25+1=26\)
Câu 4:
\(4^{15}.25^{15}+2^{30}.25^{15}\)
\(=(4^{15}+2^{30}).25^{15}\)
\(=(2^{30}+2^{30}).25^{15}\)
\(=2.2^{30}.25^{15}\)
\(=2^{31}.(5^2)^{15}\)
\(=2^{31}.5^{30}\)
\(=2.(2^{30}.5^{30})\)
\(=2.10^{30}\)