You're given six logarithmic expressions to evaluate. Let’s solve each one step by step and explain the reasoning.
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1. log₂(16)
This asks: *“To what power must 2 be raised to get 16?”*
We know:
> 2⁴ = 16
✔ So,
log₂(16) = 4
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2. log₃(27)
This asks: *“To what power must 3 be raised to get 27?”*
We know:
> 3³ = 27
✔ So,
log₃(27) = 3
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3. log(1000)
When no base is written, it means
base 10 (common logarithm).
So this is:
log₁₀(1000)
Ask: *“To what power must 10 be raised to get 1000?”*
> 10³ = 1000
✔ So,
log(1000) = 3
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4. log₃(1/9)
This asks: *“To what power must 3 be raised to get 1/9?”*
Note that:
> 1/9 = 3⁻²
Because 3² = 9 → 3⁻² = 1/9
✔ So,
log₃(1/9) = -2
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5. 5^(log₅(14))
This is a classic
inverse function property.
Recall the identity:
>
a^(logₐ(x)) = x, for a > 0, a ≠ 1, x > 0
Here, base is 5, and we’re raising 5 to the power of log₅(14). So:
✔ 5^(log₅(14)) = 14
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6. log₉(1/3)
This asks: *“To what power must 9 be raised to get 1/3?”*
Let’s write everything in terms of base 3:
- 9 = 3²
- 1/3 = 3⁻¹
So let x = log₉(1/3)
Then by definition:
> 9^x = 1/3
> (3²)^x = 3⁻¹
> 3^(2x) = 3⁻¹
Since bases are equal, set exponents equal:
> 2x = -1
> x = -1/2
✔ So,
log₉(1/3) = -1/2
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##
✔ Final Answers:
1.
log₂(16) = 4
2.
log₃(27) = 3
3.
log(1000) = 3
4.
log₃(1/9) = -2
5.
5^(log₅(14)) = 14
6.
log₉(1/3) = -1/2
These solutions use basic logarithmic definitions, exponent rules, and inverse properties. Great practice!
Parent Tip: Review the logic above to help your child master the concept of logarithms.