Combine Logs: Combine the left side using the product rule for logarithms: log2(a)+log2(b)=log2(ab). log2(2x)+log2(x−7)=log2(2x⋅(x−7)).
Simplify Left Side: Now we have log2(2x∗(x−7))=log2(4x). Simplify the left side: 2x∗(x−7)=2x2−14x.
Set Equations Equal: Since the bases of the logarithms are the same, we can set the arguments equal to each other: 2x2−14x=4x.
Subtract and Simplify: Subtract 4x from both sides to get a quadratic equation: 2x2−14x−4x=0. This simplifies to 2x2−18x=0.
Factor Common Factor: Factor out the common factor of 2x: 2x(x−9)=0.
Set Factors Equal: Set each factor equal to zero: 2x=0 or x−9=0.
Solve Equations: Solve each equation: x=0 or x=9.
Check Solutions: Check for extraneous solutions by plugging x back into the original equation.For x=0: log2(2⋅0)+log2(0−7) does not exist because log of a negative number is undefined.
Check Solutions: Check for extraneous solutions by plugging x back into the original equation.For x=0: log2(2⋅0)+log2(0−7) does not exist because log of a negative number is undefined.For x=9: log2(2⋅9)+log2(9−7)=log2(4⋅9) checks out because log2(18)+log2(2)=log2(36) and 18⋅2=36.
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