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Solve the exponential equation by taking the logarithm on both sides. 5^(x+8)=7

Sagot :

Answer:

x = (log₅7) - 8

Explanation:

Given;

[tex]5^{x+8}[/tex] = 7

Take log of both sides;

log₁₀([tex]5^{x+8}[/tex]) = log₁₀7               -------------(ii)

From the laws of logarithm remember that;

logₐ xⁿ = n logₐ x

Equation (ii) can then be written as;

(x + 8)log₁₀5 = log₁₀7

Divide both sides by log₁₀5

(x + 8) = [tex]\frac{log_{10}7}{log_{10}5}[/tex]                -----------(iii)

From the laws of logarithm, remember that;

[tex]\frac{log_{a}x}{log_{a}y} = log_yx[/tex]

Equation (iii) can thus be written as;

(x + 8) = log₅7

x + 8 = log₅7

Make x subject of the formula;

x = (log₅7) - 8