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Find the exact value for x in the following equation log2(x+4)=2−log2(1/8)

Mathematics

ScanSolve AI Answer

Answer

28

Step-by-step solution

6 steps

Here's the solution for question 8:

The problem asks to find the exact value for xx in the equation:

log⁡2(x+4)=2−log⁡218\log_2(x+4) = 2 - \log_2 \frac{1}{8}
  1. Move all logarithmic terms to one side of the equation.

    Add log⁡218\log_2 \frac{1}{8} to both sides:

    log⁡2(x+4)+log⁡218=2\log_2(x+4) + \log_2 \frac{1}{8} = 2
  2. Simplify the term log⁡218\log_2 \frac{1}{8}.

    We know that 18=2−3\frac{1}{8} = 2^{-3}.

    log⁡218=log⁡2(2−3)=−3\log_2 \frac{1}{8} = \log_2 (2^{-3}) = -3

    Substitute this value back into the equation:

    log⁡2(x+4)+(−3)=2\log_2(x+4) + (-3) = 2 log⁡2(x+4)−3=2\log_2(x+4) - 3 = 2
  3. Isolate the logarithm term.

    Add 3 to both sides:

    log⁡2(x+4)=2+3\log_2(x+4) = 2 + 3 log⁡2(x+4)=5\log_2(x+4) = 5
  4. Convert the logarithmic equation to an exponential equation.

    The definition of a logarithm states that if log⁡bA=C\log_b A = C, then bC=Ab^C = A.
    Here, b=2b=2, A=(x+4)A=(x+4), and C=5C=5.

    25=x+42^5 = x+4
  5. Solve for xx.

    Calculate 252^5:

    32=x+432 = x+4

    Subtract 4 from both sides:

    x=32−4x = 32 - 4 x=28x = 28
  6. Verify the solution.

    For log⁡2(x+4)\log_2(x+4) to be defined, x+4>0x+4 > 0.
    If x=28x=28, then 28+4=32>028+4 = 32 > 0, which is valid.

    The final answer is 28\boxed{28}.

    2 zimekamilika. Zimebaki 3 leo — tuma inayofuata.

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