Question

[Nguyễn Thị Thùy Trâm]

a) 4 mũ x = 64

b) 3 mũ x-1 = 27

c) 26 + 8x - 6x = 46

d) 25 < hoặc bằng 5 mũ x < hoặc bằng 625 

e) 10 + 2x = 4 mũ 5 : 4 mũ 3

Answer 1

[Ngọc Trân]

a)4^x=64

4^x=4^3

<=>x=3

b)3^x-1=27

3^x-1=3^3

<=>x-1=3

x=3+1

x=4

c)26+8x-6x=46

26+x(8-6)=46

26+2x=46

2x=46-26

2x=20

x=20:2

x=10

d)\(25\le5^x\le625\)

<=>\(5^2\le5^x\le5^4\)

<=>\(2\le x\le4\)

<=>\(x\in\left\{2;3;4\right\}\)

e)10+2x=4^5:4^3

10+2x=4^5-3

10+2x=4^2

10+2x=16

2x=16-10

2x=6

x=6:2

x=3

Answer 2

[ghost river]

a) 4^x = 64 
\(\Rightarrow\)4^x = 4³
\(\Rightarrow\)x = 3
b) 3^{x - 1} = 27
\(\Rightarrow\)3^{x - 1} = 3³
\(\Rightarrow\)x - 1 = 3
\(\Rightarrow\)x = 4
c) 26 + 8x - 6x = 46
\(\Rightarrow\)26 + 2x = 46
\(\Rightarrow\)2x = 46 - 26
\(\Rightarrow\)2x = 20
\(\Rightarrow\)x = 10
d) 25 \(\le\)5^x \(\le\)625
\(\Rightarrow\)5²\(\le\)5^x\(\le\)5⁴
\(\Rightarrow\)x \(\in\){ 2 ; 3 ; 4 }
e) 10 + 2x = 4⁵ : 4³
\(\Rightarrow\)10 + 2x = 4² = 16
\(\Rightarrow\)2x = 16 - 10
\(\Rightarrow\)2x = 6
\(\Rightarrow\)x = 3