5^x-11 - 2.5² = 3.5³

5^x-11 - 2.25 = 3.125

5^x-11 - 50 = 375

5^x-11 = 375 + 50

5^x-11 = 425

.....

=>x thuộc rỗng nhé

5^x-11-2.25=3.125

5^x-11-50=375

5^x-11=375+50

5^x-11=425

đề sai rồi vì 5 mũ mấy cũng ko bằng 425 đâu

\(\Leftrightarrow5^x\cdot625-3\cdot5^x\cdot125=2\cdot5^{11}\)

\(\Leftrightarrow5^x\cdot250=2\cdot5^{11}\)

\(\Leftrightarrow5^x=5^8\)

hay x=8

giup dùm zs chìu nay làm òi T-T

ai tick cho mình đi 

mình sẽ cảm ơn!!!!!!

thanks

Lời giải:

1.

$3^{x+2}+4.3^{x+1}=7.3^6$

$3^{x+1}.3+4.3^{x+1}=7.3^6$

$3^{x+1}(3+4)=7.3^6$

$3^{x+1}.7=7.3^6$

$\Rightarrow 3^{x+1}=3^6$

$\Rightarrow x+1=6$

$\Rightarrow x=5$

2.

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

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

$5^{x+3}(5-3)=2.5^{11}$

$2.5^{x+3}=2.5^{11}$

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

$\Rightarrow x+3=11$

$\Rightarrow x=8$

3.

$4^{x+3}-3.4^{x+1}=13.4^{11}$

$4^{x+1}.4^2-3.4^{x+1}=13.4^{11}$

$4^{x+1}.16-3.4^{x+1}=13.4^{11}$

$13.4^{x+1}=13.4^{11}$

$\Rightarrow 4^{x+1}=4^{11}$

$\Rightarrow x+1=11$
$\Rightarrow x=10$

\(5^{x+4}-3.5^{x+3}=2.5^{11}\)

\(\Rightarrow5^x.5^4-3.5^x.5^3=2.5^{11}\)

\(\Rightarrow5^x.5^3\left(5-3\right)=2.5^{11}\)

\(\Rightarrow5^x.2=2.5^8\)

\(\Rightarrow5^x=5^8\)

\(\Rightarrow x=8\)

Vậy \(x=8\)

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