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Solve for [tex]\( x \)[/tex].

[tex]\[ 2^{x+1} + 2^x + 2^{x-1} = 28 \][/tex]


Sagot :

Certainly! Let's solve the exponential equation [tex]\( 2^{x+1} + 2^x + 2^{x-1} = 28 \)[/tex] step by step.

First, we rewrite the terms involving exponents of [tex]\(2\)[/tex] in a simplified form. Observe the exponents:
- [tex]\(2^{x+1}\)[/tex] can be rewritten as [tex]\(2 \cdot 2^x\)[/tex].
- [tex]\(2^{x-1}\)[/tex] can be rewritten as [tex]\(\frac{1}{2} \cdot 2^x\)[/tex].

Now, substitute these into the equation:
[tex]\[ 2 \cdot 2^x + 2^x + \frac{1}{2} \cdot 2^x = 28 \][/tex]

Next, we notice that all terms contain [tex]\(2^x\)[/tex]. So, let's factor [tex]\(2^x\)[/tex] out of the equation:
[tex]\[ 2^x (2 + 1 + \frac{1}{2}) = 28 \][/tex]

Combine the constants inside the parentheses:
[tex]\[ 2 + 1 + \frac{1}{2} = 3 + \frac{1}{2} = \frac{6}{2} + \frac{1}{2} = \frac{7}{2} \][/tex]

So the equation becomes:
[tex]\[ 2^x \cdot \frac{7}{2} = 28 \][/tex]

To isolate [tex]\(2^x\)[/tex], multiply both sides of the equation by [tex]\(\frac{2}{7}\)[/tex]:
[tex]\[ 2^x = 28 \cdot \frac{2}{7} = 4 \cdot 2 = 8 \][/tex]

We now have:
[tex]\[ 2^x = 8 \][/tex]

Recognize that [tex]\(8\)[/tex] can be written as [tex]\(2^3\)[/tex]:
[tex]\[ 2^x = 2^3 \][/tex]

Since the bases are identical, we can equate the exponents:
[tex]\[ x = 3 \][/tex]

Therefore, the solution to the equation [tex]\(2^{x+1} + 2^x + 2^{x-1} = 28\)[/tex] is:
[tex]\[ x = 3 \][/tex]