a)16^x<128⁴

(2⁴)^x<(2⁷)⁴

2^4x<2²⁸

=> 4x<28

4x<4.7

=> x< 7

Vậy x thuộc{0;1;.....;6}

ta có : 16^x < 128^4

suy ra:2^4x < (2^7)^4

2^4x < 2^28

4x <28

x=(0,1,2,3,4,5,6)

x thuộc {1;2;3;4;5;6}

chúc bạn học tốt

bye

3^2x + 3^x + 3 = 759

3^x.3^x + 3^x + 3 = 759

3^x.3^x + 3^x = 759 - 3

3^x.3^x + 3^x = 756

3^x(3^x + 1) = 756

3^x(3^x + 1) = 27.28

=> 3^x = 27

3^x = 3³

=> x = 3

5^x.5^(x+1).5^(x+2).2^18<=10^18=2^18.5^18

x+x+1+x+2<=18

3x+3<=18

x+1<=6

x<=5

nếu tự nhiện thì x=(0,1,2,3,4,5)

b)

\(5^x.5^{x+1}.5^{x+2}=5^x.5^x.5.5^x.5^2=5^{x+x+x+1+3}=5^{3x+3}\le10^{18}:2^{118}\)

\(=>5^{3x+3}\le5^{18}=>3x+3\le18=>x\le5=>x\in\left\{0;1;2;3;4;5\right\}\)

**** bn, câu a tự lm nhé

a) 25+x=0

   x=0-25

  x=-25

b)\(2^x:2^{19}=2^{25}\)

\(2^x=2^{25}.2^{19}\)

\(2^x=2^{44}\)

=>x=44

c)\(5^x.5^{18}=5^{54}\)

\(5^x=5^{54}:5^{18}\)

\(5^x=5^{36}\)

=>x=36

TL :

a) \(25+x=0\)

\(x=0-25\)

\(x=-25\)

b) \(2^x:2^{19}=2^{35}\)

\(2^x=2^{25}.2^{19}\)

\(2^x=2^{44}\)

\(\Rightarrow x=44\)

c) \(5^x.5^{18}=5^{54}\)

\(5^x=5^{54}:5^{18}\)

\(5^x=5^{36}\)

\(\Rightarrow x=36\)

Học tốt

a,25+x=0

\(\Rightarrow\)x= 0-25

\(\Rightarrow\)x= -25

Vậy x=-25

b, 2\(^x\): 2\(^{19}\)=2\(^{25}\)

\(\Rightarrow\)2\(^x\)= 2\(^{25}\). 2\(^{19}\)= 2\(^{25+19}\)

\(\Rightarrow\)2\(^x\)= 2\(^{44}\)

\(\Rightarrow\)x = 44

Vậy x=44

c, 5\(^x\). 5\(^{18}\)= 5\(^{54}\)

5\(^x\)= 5\(^{54}\): 5\(^{18}\)= 5\(^{54-18}\)

\(\Rightarrow\)5\(^x\)= 5 \(^{36}\)

\(\Rightarrow\)x= 36

vậy x = 36