Chapter 5: Problem 29
Solve the equation. $$ 4 x^{3} e^{-3 x}-3 x^{4} e^{-3 x}=0 $$
Short Answer
Expert verified
The solutions are \(x = 0\) and \(x = \frac{4}{3}\).
Step by step solution
01
Factor the Equation
The given equation is \(4x^3 e^{-3x} - 3x^4 e^{-3x} = 0\). We can factor out the common term \(x^3 e^{-3x}\), which simplifies the equation to \(x^3 e^{-3x} (4 - 3x) = 0\).
02
Apply the Zero Product Property
According to the Zero Product Property, if a product of factors is zero, at least one of the factors must be zero. Set each factor equal to zero: \(x^3 e^{-3x} = 0\) and \(4 - 3x = 0\).
03
Solve for \(x\) from the First Factor
The factor \(x^3 e^{-3x} = 0\) implies that either \(x^3 = 0\) or \(e^{-3x} = 0\). Since the exponential function \(e^{-3x}\) is never zero, we only consider \(x^3 = 0\), which gives the solution \(x = 0\).
04
Solve for \(x\) from the Second Factor
The equation \(4 - 3x = 0\) can be simplified by solving for \(x\). Subtract 4 from both sides to get \(-3x = -4\), then divide both sides by \(-3\) to find \(x = \frac{4}{3}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Factorization
Understanding factorization in algebra is like finding the building blocks of a complex expression. It involves breaking down an expression into simpler elements called factors, which when multiplied together give back the original expression.
In our problem, the expression given is:
In our problem, the expression given is:
- \(4x^3 e^{-3x} - 3x^4 e^{-3x} = 0\)
- \(x^3 e^{-3x} (4 - 3x) = 0\)
Zero Product Property
The Zero Product Property is a fantastic logical rule that helps you solve equations like a pro!
When you have several factors multiplied together equating to zero, one (or more) of those factors must also be zero.Our factorized equation from before is:
When you have several factors multiplied together equating to zero, one (or more) of those factors must also be zero.Our factorized equation from before is:
- \(x^3 e^{-3x} (4 - 3x) = 0\)
- \(x^3 e^{-3x} = 0\)
- \(4 - 3x = 0\)
Exponential function
Exponential functions can seem a bit mysterious, but they're powerful and incredibly useful in mathematics. An exponential function is expressed as \(e^x\) and represents constant growth or decay.
In our equation, it is part of the term \(e^{-3x}\).A key property to note is that the exponential function \(e^x\) never equals zero for any real number \(x\). This fact simplifies solving because if you try to solve:
In our equation, it is part of the term \(e^{-3x}\).A key property to note is that the exponential function \(e^x\) never equals zero for any real number \(x\). This fact simplifies solving because if you try to solve:
- \(e^{-3x} = 0\)
Polynomial roots
Solving for polynomial roots involves finding the values of \(x\) that make the polynomial zero. The roots can tell us a lot about the polynomial function, like where it intersects with the x-axis.
From our original factorized equation, we have:
From our original factorized equation, we have:
- \(x^3 = 0\): The only root here is \(x = 0\).
- \(4 - 3x = 0\): Simplifies to \(x = \frac{4}{3}\).