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Zorluk: KolayIndices and Logarithms

If log⁡2(x+3)+log⁡24=5\log_2 (x + 3) + \log_2 4 = 5, what is the value of xx?

  1. A
    2525
  2. 55Cevap
  3. C
    1818
  4. D
    33

Cevap

The value of xx is 55.
Using the logarithmic addition property log⁡b(M)+log⁡b(N)=log⁡b(M⋅N)\log_b (M) + \log_b (N) = \log_b (M \cdot N), the equation log⁡2(x+3)+log⁡24=5\log_2(x+3) + \log_2 4 = 5 becomes log⁡2[4(x+3)]=5\log_2[4(x+3)] = 5. Converting to index form gives 4(x+3)=25=324(x+3) = 2^5 = 32. Dividing by 44 yields x+3=8x + 3 = 8, so x=5x = 5.

Adım Adım Çözüm

1
Apply the product rule of logarithms: log⁡bA+log⁡bB=log⁡b(A⋅B)\log_b A + \log_b B = \log_b (A \cdot B)
\log_2 [4(x + 3)] = 5
Logarithms with the same base that are added together can be combined by multiplying their arguments.
2
Convert the logarithmic equation into its equivalent exponential form
4(x + 3) = 2^5 = 32
If log⁡bY=c\log_b Y = c, then Y=bcY = b^c.
3
Divide both sides by 4 and solve for xx
x + 3 = 8 \implies x = 5
Linear algebraic simplification.

Anahtar Kavram

Product Law of Logarithms and Log-to-Exponential Conversion
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