Asked by Andrea Noriega on Jul 06, 2024

verifed

Verified

Solve the logarithmic equation. Round your answer to two decimal places. log⁡2(x−1) +log⁡2(x+2) =3\log _ { 2 } ( x - 1 ) + \log _ { 2 } ( x + 2 ) = 3log2(x1) +log2(x+2) =3

A) x=9.00x = 9.00x=9.00
B) x=2.70x = 2.70x=2.70
C) x=3.50x = 3.50x=3.50
D) x=0.14x = 0.14x=0.14
E) x=−3.70x = - 3.70x=3.70

Decimal Places

The number of digits to the right of a decimal point in a number.

  • Solve equations involving logarithms and comprehend their importance within mathematical frameworks.
verifed

Verified Answer

AW
Aytin WarsameJul 09, 2024
Final Answer :
B
Explanation :
Using the product rule of logarithms, we can simplify the left side of the equation:
log⁡2((x−1)(x+2))=3\log_2((x-1)(x+2))=3log2((x1)(x+2))=3
Rewriting the equation in exponential form, we have:
(x−1)(x+2)=23=8(x-1)(x+2)=2^3=8(x1)(x+2)=23=8
Expanding the left side, we get:
x2+x−2=0x^2+x-2=0x2+x2=0
Using the quadratic formula, we can solve for $x$:
x=−1±1+4(2)2x=\frac{-1\pm\sqrt{1+4(2)}}{2}x=21±1+4(2)
x=−1±32x=\frac{-1\pm 3}{2}x=21±3
This gives us two possible solutions: $x=1$ and $x=-2$. However, we need to check if these solutions satisfy the original equation.
When $x=1$, the left side of the equation becomes $\log_2(2)+\log_2(3)=1+\log_2(3)$, which is not equal to 3. Therefore, $x=1$ is not a solution.
When $x=-2$, the left side of the equation becomes $\log_2(-3)+\log_2(0)$, but logarithms are not defined for negative or zero values. Therefore, $x=-2$ is also not a solution.
Thus, the only valid solution is $x=\frac{-1+3}{2}=1$. However, this answer does not appear as one of the choices.
The closest choice to $1$ is $2.70$, which is option B.