Question

Bài 1: tìm x

a) 2^2x.2^4=1024

b) 2.3^x=10.3^12+8.27^4

c) 5^8.25^x+1=5^17

d) 3^x-1+3^x-4=28.243

e) (2x-4)^5=(2x-4)^3

Answer 1

a, 2^6x = 1024 <=> x=1024:2^6 <=>x=1024:64 <=>x=16 b,2.3^x=10.3^12+8.3^12 <=>2.3^x=3^12.(10+8) <=>2.3^x=3^12.18 <=>3^x=9 <=>3^x=3^2 <=>x=2 6,(2x-4)^5:(2x-4)^3=0 <=>(2x-4)^2=0 <=>2x-4=0 <=>2x=4 <=>x=2 hai câu kia hơi dài mà mình mỏi tay quá , sorry bạn ! bạn hãy cố gắng đưa chúng về cùng cơ số nhé ! sẽ giải ra nhé ! goodluck !

Answer 2

a) \(2^{2x}.2^4=1024\)

\(2^{2x}=1024:2^4\)

\(2^{2x}=1024:16\)

\(2^{2x}=64\)

\(2^{2x}=2^6\)

\(\Rightarrow2x=6\)

\(\Rightarrow x=3\)

vay \(x=3\)

b) \(2.3^x=10.3^{12}+8.27^4\)

\(2.3^x=2.5.3^{12}+2^3.\left(3^3\right)^4\)

\(2.3^x=2.5.3^{12}+2^3.3^{12}\)

\(2.3^x=2.3^{12}.\left(5+2^2\right)\)

\(2.3^x=2.3^{12}.9\)

\(2.3^x=2.3^{12}.3^2\)

\(2.3^x=2.3^{14}\)

\(\Rightarrow x=14\)

vay \(x=14\)

c) \(5^8.25^x+1=5^{17}\)

\(5^8.\left(5^2\right)^x+1=5^{17}\)

\(5^8.5^{2x}+1=5^{17}\)

\(5^{8+2x}=5^{17}-1\)

e) \(\left(2x-4\right)^5=\left(2x-4\right)^3\)

\(\left(2x-4\right)^5-\left(2x-4\right)^3=0\)

\(\left(2x-4\right)\left[\left(2x-4\right)^2-1\right]=0\)

\(\left(2x-4\right)\left(2x-4-1\right)\left(2x-4+1\right)=0\)

\(\left(2x-4\right)\left(2x-5\right)\left(2x-3\right)=0\)

\(\Rightarrow2x-4=0\)hoac  \(\orbr{\begin{cases}2x-5=0\\2x-3=0\end{cases}}\)

\(\Rightarrow2x=4\)hoac \(\orbr{\begin{cases}2x=5\\2x=3\end{cases}}\)

 \(\Rightarrow x=2\)hoac \(\orbr{\begin{cases}x=\frac{5}{2}\\x=\frac{3}{2}\end{cases}}\)

              vay \(x=2\)hoac \(\orbr{\begin{cases}x=\frac{5}{2}\\x=\frac{3}{2}\end{cases}}\)