The product of all solutions of the equation ( e^{(5*(\log_e x)^2) + 3} = x^8 ), ( x > 0 ), is: (1) ( e^{8/5} ) (2) ( e^{6/5} ) (3) ( e^2 ) (4) ( e )
Detailed Explanation
Key Ideas You Need
| Concept | Why it Matters Here |
|---|---|
| Natural Log () | Converts a power of into a simple number you can add/subtract. |
| Taking on Both Sides | Keeps the equation balanced while removing the outer shell. |
| Substitution () | Turns a messy expression into a clean quadratic. |
| Quadratic Formula / Factoring | Solves for quickly. |
| Back-Substitution () | Translates the answers back into . |
| Product of Roots in Same Base | When two numbers are and , their product is , so you just add exponents. |
Logical Chain of Steps
- Recognise the variable in both exponent and base: sits inside and also as a base ().
- Remove the outer exponential by applying to both sides. This is legal because (domain of ).
- Use substitution so the equation becomes a standard quadratic.
- Solve the quadratic using the discriminant or factoring.
- Convert back to by exponentiating ().
- Multiply the solutions; since both are powers of , simply add their exponents.
These six moves turn a daunting mixed log-exponential problem into a short, syllabus-friendly puzzle.
Simple Explanation (ELI5)
Imagine a See-Saw of Numbers
-
Think of
ln(log basee) as a magical magnifying glass that turns numbers into new ones so we can add or multiply them more easily. -
Our see-saw equation is
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Taking the
lnon both sides is like peeking under the same magnifying glass on both ends of the see-saw so the balance is still fair. -
After this peek, the big scary power falls down to a neat quadratic (something that looks like ).
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Quadratics are like easy Lego bricks: solve for using the formula, then turn back () to get our original .
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Finally, multiply the two answers together. A fun surprise—you just add their exponents when the bases are both !
That’s it. 😊
Step-by-Step Solution
Step-by-Step Solution
Given
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Take natural log on both sides
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Substitute .
Rearrange to standard quadratic:
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Solve the quadratic
Discriminant:
Roots:
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Back-substitute for
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Product of the solutions
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Match with options
Option (1):
[\boxed{e^{8/5}}]
Examples
Example 1
Radioactive decay half-life calculations often use to linearise an exponential curve.
Example 2
Compound interest problems simplify when you express growth factors as and then take logs.
Example 3
Population growth models use substitution to turn logistic equations into linear or quadratic forms.
Visual Representation
References
- [1]NCERT Mathematics Class 12 – Chapter on Continuity and Differentiability (Log and Exponential Basics)
- [2]I.A. Maron – Problems in Calculus of One Variable (Logarithm tricks)
- [3]R.D. Sharma – Algebra: Quadratic Equations section
- [4]MIT OpenCourseWare – Single Variable Calculus video lectures (Exponential & Logarithmic Functions)