Câu hỏi của Dragonmaster

Question

a ) 4 . 3^x-1 + 2 . 3^x+2 = 4 . 3^6 + 2 . 3^9

b ) 5^x+4 - 3 . 5^x+3 = 2 . 5^11

c ) 11 . 6^x-1 = 11 . 6^11 + 2 . 6^13

JakiNatsumi · Accepted Answer

$4.3^{x-1}+2.3^{x+2}=4.3^6+2.3^9$

$3^{x-1}.\left(4+2.3^3\right)=3^6.\left(4+2.3^3\right)$

$\Leftrightarrow3^{x-1}=3^6$

$\Leftrightarrow x-1=6$

$\Leftrightarrow x=7$

Vậy $x=7$Câu trả lời: $4.3^{x-1}+2.3^{x+2}=4.3^6+2.3^9$

$3^{x-1}.\left(4+2.3^3\right)=3^6.\left(4+2.3^3\right)$

$\Leftrightarrow3^{x-1}=3^6$

$\Leftrightarrow x-1=6$

$\Leftrightarrow x=7$

Vậy $x=7$

JakiNatsumi · Answer

$5^{x+4}-3.5^{x+3}=2.5^{11}$

$\Leftrightarrow5^{x+3}.\left(5-3\right)=2.5^{11}$

$\Leftrightarrow5^{x+3}.2=2.5^{11}$

$\Leftrightarrow5^{x+3}=5^{11}$

⇔$x+3=11$

$\Leftrightarrow x=8$

Vậy $x=8$

$11.6^{x-1}=11.6^{11}+2.6^{13}$

$\Rightarrow11.6^{x-1}=6^{11}.\left(11+2.36\right)$

$\Rightarrow11.6^{x-1}=6^{11}.83$Câu trả lời: $5^{x+4}-3.5^{x+3}=2.5^{11}$