Chapter 1: Problem 69
Find the real solutions of each equation. $$ 3 x^{-2}-7 x^{-1}-6=0 $$
Short Answer
Expert verified
The solutions are \( x = -\frac{3}{2} \) and \( x = \frac{1}{3} \).
Step by step solution
01
Rewrite the Equation
Rewrite the given equation by substituting a new variable. Let \( y = x^{-1} \). The equation becomes: \[ 3 y^2 - 7 y - 6 = 0 \]
02
Factor the Quadratic Equation
Now, factor the quadratic equation \( 3 y^2 - 7 y - 6 = 0 \). The factors are: \[ (3y + 2)(y - 3) = 0 \]
03
Solve for y
Solve for the variable \( y \) using the factored equation: \[ 3y + 2 = 0 \implies y = -\frac{2}{3} \] \[ y - 3 = 0 \implies y = 3 \]
04
Substitute Back the Original Variable
Replace \( y \) with \( x^{-1} \). We get two equations to solve for \( x \): \[ x^{-1} = -\frac{2}{3} \implies x = -\frac{3}{2} \] \[ x^{-1} = 3 \implies x = \frac{1}{3} \]
05
Check for Real Solutions
Verify that the solutions we found are real numbers, which they are. Therefore, the real solutions to the equation are: \( x = -\frac{3}{2} \) and \( x = \frac{1}{3} \)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
quadratic equations
A quadratic equation is a second-order polynomial equation in a single variable. It typically follows the standard form:
cannot be solved easily using simple algebraic methods. To find the roots or solutions of a quadratic equation, we often use methods like factoring, completing the square, or applying the quadratic formula:
The quadratic formula is especially useful when the equation cannot be factored easily. It's given by: In the context of the given exercise, rewriting the equation using the new variable converts the problem into a quadratic equation. The next step involves solving this quadratic equation to find the solutions.
cannot be solved easily using simple algebraic methods. To find the roots or solutions of a quadratic equation, we often use methods like factoring, completing the square, or applying the quadratic formula:
The quadratic formula is especially useful when the equation cannot be factored easily. It's given by: In the context of the given exercise, rewriting the equation using the new variable converts the problem into a quadratic equation. The next step involves solving this quadratic equation to find the solutions.
substitution method
The substitution method is a powerful technique used to simplify complex equations. In this exercise, we started with where is a new variable representing. By making this substitution, we transformed the original equation into a simpler quadratic form:
For example, in the step-by-step solution:
- This makes it easier to handle since quadratic equations have well-established methods for finding solutions.
- After solving the quadratic equation for we substitute back to find the values of the original variable
For example, in the step-by-step solution:
- We let
- The equation becomes
- Once we find we revert to find by solving equations
factoring polynomials
Factoring is one of the primary methods for solving quadratic equations. It involves expressing the quadratic polynomial as a product of two binomials. The factored form of a quadratic polynomial helps us identify the roots easily. Consider the quadratic equation from the exercise:
- First, we factorize it as
- This factorization allows us to solve the equation by setting each factor equal to zero:
- Solving these simple equations gives the values of
inverse functions
Inverse functions reverse the effect of the original function. If a function
- For the given exercise, after substitution and solving for we need to go back and find the values of Here, functions as an inverse function. When we find
- This involves reversing the change made by substituting, essentially applying the inverse function. In this case:
- · Solving gives us the real solutions:
- The notion of inverse functions is critical in solving equations where a variable substitution has been used. It ensures that we find the correct solutions to the original problem.