x=3

\(\Rightarrow5^{2x-3}=5^2\cdot3+5^2\cdot2=5^2\cdot5=5^3\\ \Rightarrow2x-3=3\\ \Rightarrow x=3\)

\(5^{2x-3}-2.5^2=5^2.3\)

\(\Rightarrow5^{2x-3}-50=75\)

\(\Rightarrow5^{2x-3}=125=5^3\)

\(\Rightarrow2x-3=3\Rightarrow2x=6\Rightarrow x=3\)

5²ˣ⁻³ - 2.5² = 5².3

5²ˣ⁻³ - 2.25 = 25.3

5²ˣ⁻³ - 50 = 75

5²ˣ⁻³ = 75 + 50

5²ˣ⁻³ = 125

5²ˣ⁻³ =5³

2x - 3 = 3

2x = 3 + 3

2x = 6

x = 6 : 2

x = 3

\(5^{2x-3}-2.5^2=5^2.3\)

\(\Leftrightarrow5^{2x}:5^3-50=75\)

\(\Leftrightarrow5^{2x}:5^3=75+50\)

\(\Leftrightarrow5^{2x}:5^3=125\)

\(\Leftrightarrow5^{2x}=125.5^3\)

\(\Leftrightarrow5^{2x}=5^3.5^3\)

\(\Leftrightarrow5^{2x}=5^6\)

\(\Leftrightarrow2x=6\)

\(\Leftrightarrow x=6:2\)

\(\Leftrightarrow x=3\)

Vậy x=3

b) 3^2x = 81

    3^2x = 3⁴

=> 2x = 4

=>   x = 2

a). 5^2x-3 – 2.5² = 5² .3 

             5^2x: 5³ = 5² .3 + 2.5² 

             5^2x: 5³ = 5² .5

                   5^2x = 5² .5.5³ 

                   5^2x = 5⁶

               => 2x = 6

                  => x=3

a, x = 28

b, x = 1

c, x = 24

d, x = 3

Đáp án cần chọn là: C

a: =>52x-3-104=156

=>52x-107=156

=>52x=263

hay x=263/52

b: =>6x-3+24-2x-3x=31

=>x+21=31

hay x=10

a, 2.(x – 5)+7 = 77

<=> 2.(x – 5) = 70 <=> x – 5 = 35 <=> x = 40

b,  x - 1 3 - 3 5 : 3 4 + 2 . 2 3 = 14

<=> x - 1 3 - 3 + 2 4 = 14

<=>  x - 1 3 = 14 + 3 - 16 = 1

<=> x – 1 = 1 <=> x = 2

c,  1 + 2 + 2 2 + 2 3 + . . . + 2 2016 = 2 x - 1 - 1

Đặt: A = 1 + 2 + 2 2 + 2 3 + . . . + 2 2016 => 2A =  2 + 2 2 + 2 3 + . . . + 2 2017

=> 2A – A = ( 2 + 2 2 + 2 3 + . . . + 2 2017 ) – ( 1 + 2 + 2 2 + 2 3 + . . . + 2 2016 )

=> A =  2 2017 - 1

Ta có:  1 + 2 + 2 2 + 2 3 + . . . + 2 2016 = 2 x - 1 - 1 =>  2 2017 - 1 =  2 x - 1 - 1 => x = 2018

d,  5 2 x - 3 - 2 . 5 2 = 5 2 . 3

<=>  5 2 x - 3 = 5 2 . 3 + 5 2 . 2

<=>  5 2 x - 3 = 5 2 . ( 3 + 2 )

<=>  5 2 x - 3 = 5 3

<=> 2x – 3 = 3 => x = 3

a) 52x - 3 - 2 . 52 = 52 . 3

x - 3/52 - 2 = 3

x = 3 + 2 + 3/52

x = 263/52

b) 740 / (x + 10) = 102 - 2 . 13

740 / (x + 10) = 76

x + 10 = 740 / 76

x + 10 = 185/19

x = 185/19 - 10

x = -5/19

c) 65 - 4x + 2 = 20140

65 - 4x = 20140 - 2

65 - 4x = 20138

4x = 65 - 20138

4x = -20073

x = -20073/4

d) 120 + 2 . (3x - 17) = 214

60 + 3 . x - 17 = 107

20 + x - 17/3 = 107/3

20 + x = 107/3 + 17/3

20 + x = 124/3

x = 124/3 - 20

x = 64/3

e) 41 - 2x + 1 = 9

42 - 2x = 9

21 - x = 9/2

x = 21 - 9/2

x = 33/2

\(5^{2x-3}-2.5^2=5^2.3\)
\(\Rightarrow5^{2x-3}=5^2.3+2.5^2\)
\(\Rightarrow5^{2x-3}=5^2\left(3+2\right)\)
\(\Rightarrow5^{2x-3}=5^2.5\)
\(\Rightarrow5^{2x-3}=5^3\)
\(\Rightarrow2x-3=3\)
\(\Rightarrow2x=6\)
\(\Rightarrow x=3\)
Vậy x = 3 
#kễnh