Combine Logs: We can use the property of logarithms that allows us to combine the sum of two logs with the same base into a single log by multiplying the arguments. So, we combine log2(4x−3) and log2(3x+5) into a single logarithm.log2((4x−3)(3x+5))=3
Exponential Form: Next, we can rewrite the equation in exponential form to eliminate the logarithm. The equation log2(y)=3 is equivalent to 23=y. (4x−3)(3x+5)=23
Calculate Right Side: Now we calculate 23 to simplify the right side of the equation.(4x−3)(3x+5)=8
Expand Left Side: We expand the left side of the equation by multiplying the binomials.4x×3x+4x×5−3×3x−3×5=812x2+20x−9x−15=8
Combine Like Terms: Combine like terms on the left side of the equation. 12x2+11x−15=8
Set Equation to Zero: Subtract 8 from both sides to set the equation to zero, which is necessary for solving a quadratic equation.12x2+11x−15−8=012x2+11x−23=0
Solve Quadratic Equation: Now we need to solve the quadratic equation. This can be done by factoring, completing the square, or using the quadratic formula. The quadratic formula is x=2a−b±b2−4ac. In this case, a=12, b=11, and c=−23.
Calculate Discriminant: We calculate the discriminant b2−4ac to determine if there are real solutions.Discriminant = 112−4(12)(−23)Discriminant = 121+1104Discriminant = 1225
Apply Quadratic Formula: Since the discriminant is positive, there are two real solutions. We proceed with the quadratic formula.x=24−11±1225
Calculate Square Root: Calculate the square root of the discriminant. 1225=35
Substitute Square Root: Substitute the square root back into the quadratic formula.x=24−11±35
Solve for x: Solve for the two possible values of x.x1=24−11+35x1=2424x1=1x2=24−11−35x2=24−46x2=12−23
Check Valid Solutions: We must check these solutions to ensure they do not make the argument of the original logarithms negative, as the logarithm of a negative number is undefined.For x1=1:4(1)−3=4−3=1 (positive)3(1)+5=3+5=8 (positive)For x2=−1223:4\left(-\frac{23}{12}\right) - 3 = -\frac{23}{3} - 3 < 0 (negative)3\left(-\frac{23}{12}\right) + 5 = -\frac{23}{4} + 5 < 0 (negative)x2=−1223 is not a valid solution because it makes the arguments of the logarithms negative.
Final Valid Solution: Therefore, the only valid solution is x1=1.
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