a) 2x.4=128
2x =128:4
2x = 32
x = 32:2
x = 16
\(2^x.4=128\)
\(\Rightarrow2^x=32\left(\text{cùng chia cho 4}\right)\)
\(\Rightarrow2^x=2^5\)
\(\Rightarrow x=5\)
\(x^{15}=x\)
\(\Rightarrow x.x.x.x.x.x....x=x\)
\(\Rightarrow x=1\)
\(16^x< 128\)
\(\Rightarrow\left(2^4\right)^x=2^7\)
\(\Rightarrow2^{4x}< 2^7\)
\(\Rightarrow4x< 7\)
\(\Rightarrow x\in\left\{0;1\right\}\)
\(\left(x^5\right)^{10}=x\)
\(\Rightarrow x^{50}< x\)
\(\Rightarrow x.x.x.x....x.x.x=x\)
\(\Rightarrow x=1\)
\(a)2^x.4=128\)
\(\Rightarrow2^x=32\)
\(\Rightarrow2^x=2^5\)
\(\Rightarrow x=5\)
\(b)x^{15}=x\)
\(\Rightarrow x=0\)hoặc \(x=1\)
\(c)16^x< 128\)
\(\Rightarrow2^{4x}< 2^7\)
\(\Rightarrow4x< 7\)
\(\Rightarrow x< \frac{4}{7}\)mà \(\)\(x\in N\)\(\Rightarrow\) Không có x thỏa mãn
