Question

[linh Nguyễn]

1,tìm x

a.\(3^x\)=81

b.\(5^{x+2}\)=125

c.\(2^3\)*\(2^{x-1}\)=64

d. 7*\(7^{n+1}\)=343

e.\(\left(x+3\right)^5\)=243

f.\(\left(2x-3\right)^6\)=64

g.\(\left(x-6\right)^3\)=\(\left(x-6\right)^2\)

h.\(\left\{\left[\left(2x+14\right):2^2-3\right]:3\right\}\)-1=0

i.\(\left\{\left[\left(x:3+17\right):10+3\cdot2^4\right]:10\right\}=5\)

2,tính

a.\(7^{3^1}\)         b.\(7^{1^3}\)      c.\(6^{1^{2^{3^4}}}\)       d.\(2017^{2^{0^{1^0}}}\)      e.\(6^3:6^2-6^2:6\)    f.\(\frac{11\cdot2^{22}\cdot3^7-9^{15}}{\left(2\cdot3^{14}\right)^2}\)

Answer 1

[truong nhat linh]

1, Ta có :

a . 81 = 3⁴ => 3^x= 3⁴ => x = 4 .

b. 125 = 5³ => 5^x+2 = 5³ =>x + 2 = 3 => x = 1

c. 2³ * 2^{x - 1} = 64

=> 2^{3 + ( x - 1 )} = 64 = 2⁶ 

^{=>  3 + ( x - 1 ) = 6} 

^{=>           x - 1   = 6 - 3 = 3}

                      ^{x  = 3 + 1}

                       ^{x  = 4}