Bài 2:
1: \(4^x=4^3\cdot4^5\)
=>\(4^x=4^8\)
=>x=8
2: \(7^x=7\cdot7^7\)
=>\(7^x=7^8\)
=>x=8
3: \(5^x=5^3\cdot5^5\)
=>x=3+5
=>x=8
4: \(8^x=8^3\cdot8^5\)
=>x=3+5=8
5: \(5^x=5^{15}:5^3=5^{15-3}=5^{12}\)
=>x=12
6: \(9^x=9^{20}:9^5\)
=>x=20-5=15
7: \(4^x=4^{15}:4^5\)
=>x=15-5=10
8: \(7^x=7^{20}:7^{10}\)
=>\(7^x=7^{10}\)
=>x=10
Bài 3:
1: \(5^x\cdot5=5^3\)
=>x+1=3
=>x=2
2:
\(3^4\cdot3^x=3^7\)
=>x+4=7
=>x=7-4=3
3: \(7^x\cdot7^7=7^9\)
=>x+7=9
=>x=9-7=2
4: \(3^2\cdot3^x=3^7\)
=>\(3^x=\dfrac{3^7}{3^2}=3^5\)
=>x=5
5: \(3^2\cdot3^x=3^7\)
=>\(3^x=\dfrac{3^7}{3^2}=3^5\)
=>x=5
6: \(7^x\cdot7^7=7^{17}\)
=>\(7^x=\dfrac{7^{17}}{7^7}=7^{10}\)
=>x=10
7: \(3^x\cdot3^7=3^{17}\)
=>\(3^x=\dfrac{3^{17}}{3^7}=3^{10}\)
=>x=10
8: \(3^2\cdot3^x=3^5\)
=>\(3^x=\dfrac{3^5}{3^2}=3^3\)
=>x=3
9: \(8^x\cdot8^8=8^8\)
=>\(8^x=\dfrac{8^8}{8^8}=1\)
=>x=0
10: \(4^3\cdot4^x=4^{15}\)
=>\(4^x=\dfrac{4^{15}}{4^3}=4^{12}\)
=>x=12
11: \(4^x\cdot4^5=4^{17}\)
=>\(4^x=\dfrac{4^{17}}{4^5}=4^{12}\)
=>x=12
12: \(3^{15}\cdot3^x=3^{30}\)
=>\(3^x=\dfrac{3^{30}}{3^{15}}=3^{15}\)
=>x=15
13: \(7^x\cdot7^{12}=7^{88}\)
=>\(7^x=\dfrac{7^{88}}{7^{12}}=7^{76}\)
=>x=76
14: \(6^{80}\cdot6^x=6^{90}\)
=>\(6^x=\dfrac{6^{90}}{6^{80}}=6^{10}\)
=>x=10
15: \(3^x\cdot3^4=3^7\)
=>\(3^x=\dfrac{3^7}{3^4}=3^3\)
=>x=3
