Ta có: A = 5 + 52 + 53 +....+ 5100

      $\Rightarrow A=\left(5+5^2\right)+\left(5^3+5^4\right)+...+\left(5^{99}+5^{100}\right)$

       $\Rightarrow A=5\left(1+5\right)+5^3.\left(1+5\right)+...+5^{99}.\left(1+5\right)$

       $\Rightarrow A=5.6+5^3.6+...+5^{99}.6$

              $A=6.\left(5+5^3+...+5^{99}\right)$ chia hết

Ta có: A = 5 + 52 + 53 +....+ 5100

      $\Rightarrow A=\left(5+5^2\right)+\left(5^3+5^4\right)+...+\left(5^{99}+5^{100}\right)$

       $\Rightarrow A=5\left(1+5\right)+5^3.\left(1+5\right)+...+5^{99}.\left(1+5\right)$

       $\Rightarrow A=5.6+5^3.6+...+5^{99}.6$

              $A=6.\left(5+5^3+...+5^{99}\right)$ chia hết

Ta có: A = 5 + 52 + 53 +....+ 5100

      $\Rightarrow A=\left(5+5^2\right)+\left(5^3+5^4\right)+...+\left(5^{99}+5^{100}\right)$

       $\Rightarrow A=5\left(1+5\right)+5^3.\left(1+5\right)+...+5^{99}.\left(1+5\right)$

       $\Rightarrow A=5.6+5^3.6+...+5^{99}.6$

              $A=6.\left(5+5^3+...+5^{99}\right)$ chia hết

Ta có: A = 5 + 52 + 53 +....+ 5100

      $\Rightarrow A=\left(5+5^2\right)+\left(5^3+5^4\right)+...+\left(5^{99}+5^{100}\right)$

       $\Rightarrow A=5\left(1+5\right)+5^3.\left(1+5\right)+...+5^{99}.\left(1+5\right)$

       $\Rightarrow A=5.6+5^3.6+...+5^{99}.6$

              $A=6.\left(5+5^3+...+5^{99}\right)$ chia hết

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

 

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

 

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

 

⇒5x=560⇒x=60

Bài 7 :

a) $3^x+3^{x+2}=9^{17}+27^{12}$

$\Rightarrow 3^x\left(1+3^2\right)={\left(3^2\right)}^{17}+{\left(3^3\right)}^{12}$

$\Rightarrow 10.3^x=3^{34}+3^{36}$

$\Rightarrow 10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}$

$\Rightarrow 3^x=3^{34}\Rightarrow x=34$

b) $5^{x+1}-5^x=100.25^{29}\Rightarrow 5^x\left(5-1\right)=4.5^2.{\left(5^2\right)}^{29}$

$\Rightarrow 4.5^x=4.25^{2.29+2}=4.5^{60}$

 

⇒5x=560⇒x=60

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Bằng 25 nhé

C nhé 

a)= 207 => hợp số

b)= 255 => hop so

c)=782 => hop so

d)=6159 =>hop so

GOOD LUCK ^_^

là 1 nhá 

vạy bằng 123