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Solve each equation for x. Give both an exact value and a decimal approximation, correct to three decimal places. (a) log³(x²−x−4)=2 exact value = decimal approximation x=

User Mjallday
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1 Answer

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The given question asks us to solve the equation:

log³(x²−x−4)=2


First, rewrite the equation in exponential form:

3^2 = x² - x - 4

Simplify the equation:

x² - x - 4 - 9 = 0
x² - x - 13 = 0

This is a quadratic equation in standard form (ax² + bx + c = 0). To solve for x, we will need to use the quadratic formula: x = [-b ± sqrt(b² - 4ac)] / 2a.

For our equation, a = 1, b = -1, and c = -13.

Substitute these values into the quadratic formula:

x = [1 ± sqrt((-1)² - 4*1*(-13))] / 2*1
x = [1 ± sqrt(1 + 52)] / 2
x = [1 ± sqrt(53)] / 2

This gives us two possible exact solutions for x:

x =1/2 + sqrt(53)/2
x = 1/2 - sqrt(53)/2

These values are irrational, meaning they cannot be exactly represented as a finite decimal or a fraction. We can, however, approximate these solutions to three decimal places:

x ≈ 4.140
x ≈ -3.140

Therefore, the solutions to the equation log³(x²−x−4)=2 are approximately x = 4.140 and x = -3.140. Exact values will be x =1/2 + sqrt(53)/2 and x = 1/2 - sqrt(53)/2.

User MatterOfFact
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