Chapter 1: Problem 19
Solve each equation. $$\frac{5}{x^{2}}-\frac{43}{x}=18$$
Short Answer
Expert verified
The solutions are \( x = \frac{1}{9} \) and \( x = -\frac{5}{2} \).
Step by step solution
01
Find a Common Denominator
The equation given is \( \frac{5}{x^{2}}-\frac{43}{x}=18 \). Notice that the common denominator of \( x^2 \) and \( x \) is \( x^2 \). Therefore, rewrite the fractions with \( x^2 \) as the denominator: \( \frac{5}{x^{2}} - \frac{43x}{x^2} = 18 \).
02
Combine the Fractions
Combine the fractions to have a single fraction on the left-hand side: \( \frac{5 - 43x}{x^2} = 18 \).
03
Clear the Denominator
Multiply both sides of the equation by \( x^2 \) to eliminate the fraction: \( 5 - 43x = 18x^2 \).
04
Rearrange the Equation
Rearrange the equation to set it to zero: \( 18x^2 + 43x - 5 = 0 \).
05
Solve the Quadratic Equation
Solve the quadratic equation using the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \). Here, \( a = 18 \), \( b = 43 \), and \( c = -5 \): Calculate the discriminant: \( b^2 - 4ac = 43^2 - 4(18)(-5) = 1849 + 360 = 2209 \).Now solve for \( x \) using the quadratic formula: \( x = \frac{-43 \pm \sqrt{2209}}{2(18)} = \frac{-43 \pm 47}{36} \).
06
Simplify the Quadratic Formula
Simplify the expressions \( x = \frac{-43 + 47}{36} = \frac{4}{36} = \frac{1}{9} \) and \( x = \frac{-43 - 47}{36} = \frac{-90}{36} = -\frac{5}{2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
quadratic formula
The quadratic formula is a powerful tool used to solve quadratic equations of the form \(ax^2 + bx + c = 0\). This formula provides the solution(s) for \(x\) as long as you know the coefficients \(a\), \(b\), and \(c\). The quadratic formula is given by: \[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]. It’s important to follow each step carefully:
- Identify the coefficients \(a\), \(b\), and \(c\) from your equation.
- Calculate the discriminant \(b^2 - 4ac\).
- Plug the values into the formula.
- Simplify to get the solutions for \(x\).
common denominator
When solving rational equations, finding a common denominator is crucial. This helps to combine fractions and simplify the equation. Here’s how you can identify and use a common denominator:
- Look at the denominators involved in each term.
- Find the lowest common multiple of these denominators.
- Rewrite each fraction with the common denominator.
discriminant
The discriminant is a component of the quadratic formula under the square root sign: \(b^2 - 4ac\). It tells us the nature of the roots (solutions) of the quadratic equation:
- If \(b^2 - 4ac > 0\), the equation has two distinct real roots.
- If \(b^2 - 4ac = 0\), the equation has exactly one real root (a repeated root).
- If \(b^2 - 4ac < 0\), the equation has two complex (imaginary) roots.