Question

Solve by using logarithms, not the same base. I have absolutely no clue how to solve so any help would be amazing, thanks

Answer 1

Answer:

-5/48

Step-by-step explanation:

(8 · 2⁷ˣ)⁴ = (1/16)⁵ˣ · 128

Take log of both sides.

log (8 · 2⁷ˣ)⁴ = log ((1/16)⁵ˣ · 128)

Use log exponent/product rules.

4 log (8 · 2⁷ˣ) = log (1/16)⁵ˣ + log 128

Use log exponent/product rules.

4 (log 8 + log (2⁷ˣ)) = 5x log (1/16) + log 128

Use log exponent rule.

4 (log 8 + 7x log 2) = 5x log (1/16) + log 128

Distribute.

4 log 8 + 28x log 2 = 5x log (1/16) + log 128

Write as powers of 2.

4 log 2³ + 28x log 2 = 5x log (2⁻⁴) + log 2⁷

Use log exponent rule.

12 log 2 + 28x log 2 = -20x log 2 + 7 log 2

Combine like terms.

5 log 2 + 48x log 2 = 0

Divide by log 2.

5 + 48x = 0

Solve for x.

x = -5/48