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Solve for [tex]\( x \)[/tex]:
[tex]\[ 16^x = 64^{x+4} \][/tex]

A. [tex]\( x = -12 \)[/tex]
B. [tex]\( x = -2 \)[/tex]
C. [tex]\( x = 2 \)[/tex]
D. [tex]\( x = 12 \)[/tex]

Sagot :

To solve the equation [tex]\(16^x = 64^{x+4}\)[/tex], let's go through the steps to find the solutions.

Given equation:
[tex]\[ 16^x = 64^{x+4} \][/tex]

First, express both sides of the equation with a common base. Notice that [tex]\(16\)[/tex] and [tex]\(64\)[/tex] can both be written as powers of [tex]\(2\)[/tex]:
[tex]\[ 16 = 2^4 \][/tex]
[tex]\[ 64 = 2^6 \][/tex]

Therefore, rewrite the equation as:
[tex]\[ (2^4)^x = (2^6)^{x+4} \][/tex]

This simplifies to:
[tex]\[ 2^{4x} = 2^{6(x+4)} \][/tex]

Since the bases are the same, we can set the exponents equal to each other:
[tex]\[ 4x = 6(x + 4) \][/tex]

Expand and simplify the equation:
[tex]\[ 4x = 6x + 24 \][/tex]

Subtract [tex]\(6x\)[/tex] from both sides:
[tex]\[ 4x - 6x = 24 \][/tex]
[tex]\[ -2x = 24 \][/tex]

Divide both sides by [tex]\(-2\)[/tex]:
[tex]\[ x = -12 \][/tex]

Thus, [tex]\(x = -12\)[/tex] is indeed one of the solutions.

The second solution seems to be more complex and contains a logarithmic term. Therefore, there is another solution:
[tex]\[ x = \frac{-\log(4096) + i\pi}{\log(2)} \][/tex]

However, only the real solution from our equation is [tex]\(x = -12\)[/tex].

Therefore, the only real value of [tex]\(x\)[/tex] that is a solution to the equation [tex]\(16^x = 64^{x+4}\)[/tex] is:

[tex]\[ x = -12 \][/tex]