Question

[Trần An Nhiên]

Tìm số tự nhiên x, sao cho:

a) 2^x.4 = 16

b) 3^x.3 = 243

c) 64.4^x= 16⁸ 

d)2^x.16^x= 1024

Answer 1

[Nguyễn Việt Lâm]

a.

\(2^x.4=16\)

\(2^x=16:4\)

\(2^x=4\)

\(2^x=2^2\)

\(x=2\)

b.

\(3^x.3=243\)

\(3^x=243:3\)

\(3^x=81\)

\(3^x=3^4\)

\(x=4\)

Answer 2

[Nguyễn Việt Lâm]

c.

\(64.4^x=16^8\)

\(4^3.4^x=\left(4^2\right)^8\)

\(4^{x+3}=4^{2.8}\)

\(4^{x+3}=4^{16}\)

\(x+3=16\)

\(x=13\)

d.

\(2^x.16^x=1024\)

\(2^x.\left(2^4\right)^x=2^{10}\)

\(2^x.2^{4x}=2^{10}\)

\(2^{x+4x}=2^{10}\)

\(2^{5x}=2^{10}\)

\(5x=10\)

\(x=2\)