Chapter 8: Problem 27
For each equation, determine what type of number the solutions are and how many solutions exist. $$y^{2}+\frac{9}{4}=4 y$$
Short Answer
Expert verified
Two distinct irrational solutions exist.
Step by step solution
01
- Move all terms to one side
First, move all terms to one side of the equation to set the equation to zero: \[ y^2 + \frac{9}{4} - 4y = 0 \]
02
- Simplify the quadratic equation
Rewrite the equation in standard quadratic form \(ay^2 + by + c = 0\). In this case: \[ y^2 - 4y + \frac{9}{4} = 0 \]
03
- Use the quadratic formula
To determine the solutions of the quadratic equation, use the quadratic formula: \[ y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] For the equation \( y^2 - 4y + \frac{9}{4} = 0 \), \(a = 1\), \(b = -4\), and \(c = \frac{9}{4}\).
04
- Calculate the discriminant
Calculate the discriminant \( \Delta = b^2 - 4ac \): \[ \Delta = (-4)^2 - 4 \cdot 1 \cdot \frac{9}{4} = 16 - 9 = 7 \]
05
- Determine the nature and number of solutions
Since the discriminant \( \Delta = 7 \) is positive and not a perfect square, there are two distinct irrational solutions.
06
- Solve for the solutions
Substitute \(a\), \(b\), and \(\Delta\) into the quadratic formula to find the solutions: \[ y = \frac{4 \pm \sqrt{7}}{2} \] Simplify to get: \[ y = 2 \pm \frac{\sqrt{7}}{2} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
discriminant
The discriminant plays an important role in understanding quadratic equations. It is a value calculated from the coefficients of the quadratic equation and reveals the nature of the roots.
For a quadratic equation in the form \(ax^2 + bx + c = 0\), the discriminant \(\Delta\) is calculated as follows:
\[\Delta = b^2 - 4ac\]
The value of \(\Delta\) tells us different things about the solutions:
For a quadratic equation in the form \(ax^2 + bx + c = 0\), the discriminant \(\Delta\) is calculated as follows:
\[\Delta = b^2 - 4ac\]
The value of \(\Delta\) tells us different things about the solutions:
- If \(\Delta > 0\), there are two distinct real solutions.
- If \(\Delta = 0\), there is exactly one real solution (also called a repeated or double root).
- If \(\Delta < 0\), the equation has two complex solutions.
quadratic formula
The quadratic formula is a tool for solving any quadratic equation \(ax^2 + bx + c = 0\). It provides the solutions directly from the coefficients of the equation without needing to factorize.
The quadratic formula is given by:
\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]
Here's a step-by-step breakdown on how to use it:
The quadratic formula is given by:
\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]
Here's a step-by-step breakdown on how to use it:
- Identify the coefficients \(a\), \(b\), and \(c\) from the quadratic equation.
- Calculate the discriminant \(\Delta = b^2 - 4ac\).
- Substitute \(b\), \(a\), and \(\Delta\) into the quadratic formula.
- Simplify the expression to find the solutions.
solution types
Quadratic equations can have different types of solutions based on the discriminant \(\Delta\). These solutions can be:
- **Distinct Real Solutions**: If \(\Delta > 0\), there are two distinct real solutions. For instance, in the given equation, \(\Delta = 7\), which means it has two distinct irrational solutions: \(2 \pm \frac{\sqrt{7}}{2}\).
- **Repeated Real Solution**: If \(\Delta = 0\), there is a single, repeated real solution. This happens when the parabola touches the x-axis at one point.
- **Complex Solutions**: If \(\Delta < 0\), the equation has two complex solutions. In this case, the solutions involve imaginary numbers, appearing as conjugate pairs.