Math  /  Algebra

QuestionCheck for extraneous solutions.
8. ln2a=9\ln 2 a=9

2

Studdy Solution

STEP 1

1. The equation ln2a=9 \ln 2a = 9 involves the natural logarithm.
2. We need to solve for a a and check if the solution is valid in the context of the original equation.

STEP 2

1. Solve the logarithmic equation for a a .
2. Check for extraneous solutions.

STEP 3

To solve for a a , we first need to rewrite the logarithmic equation in its exponential form. Recall that if lnb=c \ln b = c , then b=ec b = e^c . Apply this to the equation:
ln2a=9 \ln 2a = 9
Rewrite it as:
2a=e9 2a = e^9

STEP 4

Next, solve for a a by dividing both sides by 2:
2a=e9 2a = e^9 a=e92 a = \frac{e^9}{2}

STEP 5

Check for extraneous solutions. Since the natural logarithm function is defined for positive arguments, we need to ensure that 2a>0 2a > 0 . Given a=e92 a = \frac{e^9}{2} , we have:
2a=e9 2a = e^9
Since e9 e^9 is positive, 2a 2a is also positive, confirming that the solution is valid and not extraneous.
The solution for a a is:
e92 \boxed{\frac{e^9}{2}}

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