Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a, 27.\(3^x\) = 243
\(3^x\) = 243 : 27
\(3^x\) = 9
\(3^x\) = 32
\(x\) = 2
b, 49.7\(^x\) = 2041
7\(^x\) = 2041: 49
7\(^x\) = 41,65
\(x\) = log741,56
\(x\) ≈ 1,916
c, 64.4\(^x\) = 4\(^5\)
4\(^x\) = 45 : 64
4\(^x\) = 4
\(x\) = 1
d, 3\(^x\) = 243
3\(^x\) = 35
\(x\) = 5
e, 2\(^{x+5}\) = 128
\(2^{x+5}\) = 27
\(x+5\) = 7
\(x\) = 7 - 5
\(x\) = 2
f, 3.3\(^x\) = 81
3\(^x\) = 81 : 3
3\(^x\) = 27
3\(^x\) = 33
\(x\) = 3
g, 25 + 5\(^x\).5\(^x\) = 650
5\(^{2x}\) = 650 - 25
5\(^{2x}\) = 625
5\(^{2x}\) = 54
2\(x\) = 4
\(x\) = 2
\(a,27.3^x=243\\ \Rightarrow3^x=243:27\\ \Rightarrow3^x=9\\ \Rightarrow3^x=3^2\\ \Rightarrow x=2\left(thoaman\right)\)
\(b,49.7^x=2041\\ \Rightarrow7^x=2041:49\\ \Rightarrow7^x=7^4:7^2\\ \Rightarrow7^x=7^{4-2}\\ \Rightarrow7^x=7^2\\ \Rightarrow x=2\left(thoaman\right)\)
\(c,64.4^x=4^5\\ \Rightarrow4^x=4^5:4^3\\ \Rightarrow4^x=4^2\\ \Rightarrow x=2\left(thoaman\right)\)
\(d,3^x=243\\ \Rightarrow3^x=3^5\\ \Rightarrow x=5\left(thoaman\right)\)
\(e,2^{x+5}=128\\ \Rightarrow2^x.2^5=2^7\\ \Rightarrow2^x=2^7:2^5\\ \Rightarrow2^x=2^2\\ \Rightarrow x=2\left(thoaman\right)\)
\(f,3.3^x=81\\ \Rightarrow3^x=81:3\\ \Rightarrow3^x=27\\ \Rightarrow3^x=3^3\\ \Rightarrow x=3\left(thoaman\right)\)
\(g,25+5^x.5^x=650\\ \Rightarrow5^{2x}=650-25\\ \Rightarrow5^{2x}=625\\ \Rightarrow5^{2x}=5^4\\ \Rightarrow2x=4\\ \Rightarrow x=4:2=2\left(thoaman\right)\)
câu h không rõ đề ?
@seven
Những câu này cũng không khó lắm, biết là em mới học có thể sẽ chưa chắc nhưng em thật sự cần câu nào em nhỉ?
\(k,125^5:25^3=5^{15}:5^6=5^9\\ l,27^6:9^3=3^{18}:3^6=3^{12}\\ m,4^{20}:2^{15}=2^{40}:2^{15}=2^{25}\\ n,24^n:2^n=3^n\cdot2^{3n}:2^n=3^n\cdot2^{2n}=12^n\\ p,64^4\cdot16^5:4^{20}=2^{24}\cdot2^{20}:2^{40}=2^4\\ q,32^4:8^6=2^{20}:2^{18}=2^2\)
a: 3x+21=57
=>3x=57-21
=>3x=36
=>\(x=\dfrac{36}{3}=12\)
b: \(2x-138=2^3\cdot3^2\)
=>\(2x-138=8\cdot9=72\)
=>2x=72+138=210
=>x=105
c: \(4x^3+12=120\)
=>\(4x^3=120-12=108\)
=>\(x^3=27=3^3\)
=>x=3
\(a)3x+21=57\\ \Leftrightarrow3x=57-21\\ \Leftrightarrow3x=36\\ \Leftrightarrow x=\dfrac{36}{3}\\ \Leftrightarrow x=12\\ b)2x-138=2^3\cdot3^2\\ \Leftrightarrow2x-138=72\\ \Leftrightarrow2x=72+138\\ \Leftrightarrow2x=210\\ \Leftrightarrow x=\dfrac{210}{2}\\ \Leftrightarrow x=105\\ c)4x^3+12=120\\ \Leftrightarrow4x^3=120-12\\ \Leftrightarrow4x^3=108\\ \Leftrightarrow x^3=\dfrac{108}{4}\\ \Leftrightarrow x^3=27\\ \Leftrightarrow x^3=3^3\\ \Leftrightarrow x=3.\)
k) \(125^5:25^3\)
\(=\left(5^3\right)^5:\left(5^2\right)^3\)
\(=5^{15}:5^6\)
\(=5^{15-6}\)
\(=5^9\)
l) \(27^6:9^3\)
\(=\left(3^3\right)^6:\left(3^2\right)^3\)
\(=3^{18}:3^6\)
\(=3^{18-6}\)
\(=3^{12}\)
m) \(4^{20}:2^{15}\)
\(=\left(2^2\right)^{20}:2^{15}\)
\(=2^{40}:2^{15}\)
\(=2^{40-15}\)
\(=2^{25}\)
n) \(24^n:2^{2n}\)
\(=6^n\cdot4^n:\left(2^2\right)^n\)
\(=6^n\cdot4^n:4^n\)
\(=6^n\)
p) \(64^4\cdot16^5:4^{20}\)
\(=\left(4^3\right)^4\cdot\left(4^2\right)^5:4^{20}\)
\(=4^{12}\cdot4^{10}:4^{20}\)
\(=4^{12+10-20}\)
\(=4^2\)
q) \(32^4:8^6\)
\(=\left(2^5\right)^4:\left(2^3\right)^6\)
\(=2^{20}:2^{18}\)
\(=2^{20-18}\)
\(=2^2\)
k: =(5^3)^5:(5^2)^3
=5^15:5^6=5^9
l: =(3^3)^6:(3^2)^3
=3^18:3^6=3^12
m: =2^40:2^15=2^25
n: \(=\dfrac{24^n}{4^n}=6^n\)
p: \(=\left(4^3\right)^4\cdot\dfrac{\left(4^2\right)^5}{4^{20}}=\dfrac{4^{12}\cdot4^{10}}{4^{20}}=4^2\)
q: \(=\left(2^5\right)^4:\left(2^3\right)^6=\dfrac{2^{20}}{2^{18}}=2^2\)