\(5^{x+1}+6\cdot5^{x+1}=875\\ 5^{x+1}\left(1+6\right)=875\\ 5^{x+1}\cdot7=875\\ 5^{x+1}=875:7\\ 5^{x+1}=125=5^3\\ \Rightarrow x+1=3\\ \Rightarrow x=2\)Vậy x = 2
\(3^x+3^{x+3}=756\\ 3^x\left(1+3^3\right)=756\\ 3^x\cdot28=756\\ 3^x=756:28\\ 3^x=27=3^3\\ \Rightarrow x=3\)Vậy x = 3
3x + 3x+3 = 756
=> 3x + 3x.33 = 756
=> 3x + 3x.27 = 756
=> 3x.(1 + 27) = 756
=> 3x.28 = 756
=> 3x = 756 : 28
=> 3x = 27 = 33
=> x = 3
5x+1 + 6.5x+1 = 875
=> 5x+1.(1 + 6) = 875
=> 5x+1.7 = 875
=> 5x+1 = 875 : 7
=> 5x+1 = 125 = 53
=> x + 1 = 3
=> x = 3 - 1
=> x = 2
a) \(5^{x+1}+6.5^{x+1}=875\)
\(\Rightarrow5^{x+1}.\left(1+6\right)=875\)
\(\Rightarrow5^{x+1}.7=875\)
\(\Rightarrow5^{x+1}=875:7\)
\(\Rightarrow5^{x+1}=125\)
\(\Rightarrow5^{x+1}=5^3\)
\(\Rightarrow x+1=3\)
\(\Rightarrow x=3-1\)
\(\Rightarrow x=2\)
Vậy \(x=2.\)
b) Câu này mình vừa làm ở dưới rồi mà bạn.
Chúc bạn học tốt!
\(5^{x+1}+6.5^{x+1}=875\\ \Leftrightarrow5^{x+1}.\left(1+6\right)=875\\ 5^{x+1}=125\Leftrightarrow5^{x+1}=5^3\\ \Leftrightarrow x+1=3\Rightarrow x=2 \)
vậy x = 2
\(3^x+3^{x+3}=756\\ \Leftrightarrow3^x+3^x.3^3=756\\ 3^x.\left(1+3^3\right)=756\\ 3^x.28=756\\ 3^x=27\Leftrightarrow3^x=3^3\\ \Rightarrow x=3\)
vạy x = 3
#tich&theo dõi
