Chapter 2: Problem 38
For the following exercises, solve the quadratic equation by using the quadratic formula. If the solutions are not real, state No Real Solution. $$ 2 x^{2}+5 x+3=0 $$
Short Answer
Expert verified
The solutions are \( x = -1 \) and \( x = -\frac{3}{2} \).
Step by step solution
01
Identify the Quadratic Equation
The quadratic equation given is \( 2x^2 + 5x + 3 = 0 \). This equation is in the standard form \( ax^2 + bx + c = 0 \), where \( a = 2 \), \( b = 5 \), and \( c = 3 \).
02
Write the Quadratic Formula
The quadratic formula is used to solve equations of the form \( ax^2 + bx + c = 0 \). It is given by: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
03
Calculate the Discriminant
The discriminant of a quadratic equation, \( b^2 - 4ac \), helps determine the nature of the roots. For the equation \( 2x^2 + 5x + 3 = 0 \), calculate the discriminant:\[ b^2 - 4ac = 5^2 - 4 \times 2 \times 3 = 25 - 24 = 1 \]
04
Determine the Nature of the Roots
Since the discriminant is \( 1 \), which is greater than zero, the equation has two distinct real roots.
05
Apply the Quadratic Formula
Substitute \( a = 2 \), \( b = 5 \), and \( c = 3 \) into the quadratic formula:\[ x = \frac{-5 \pm \sqrt{1}}{4} \]
06
Calculate the Roots
Evaluate the expression for the roots:- First root: \( x = \frac{-5 + 1}{4} = \frac{-4}{4} = -1 \)- Second root: \( x = \frac{-5 - 1}{4} = \frac{-6}{4} = -\frac{3}{2} \)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equation
A quadratic equation is a second-degree polynomial equation in a single variable with the form \( ax^2 + bx + c = 0 \). It features three key components: the quadratic term \( ax^2 \), where \( a eq 0 \); the linear term \( bx \); and the constant term \( c \). The graph of a quadratic equation is a parabola that can open upwards or downwards depending on the sign of coefficient \( a \).
- If \( a > 0 \), the parabola opens upwards.
- If \( a < 0 \), it opens downwards.
Discriminant
The discriminant is a key part of the quadratic formula that helps determine the nature of the roots of a quadratic equation. It is given by the expression \( b^2 - 4ac \), where \( a \), \( b \), and \( c \) are the coefficients of the equation \( ax^2 + bx + c = 0 \). The discriminant provides insight into the type and number of roots the equation has:
- If \( b^2 - 4ac > 0 \), there are two distinct real roots.
- If \( b^2 - 4ac = 0 \), there is exactly one real root, which implies a repeated, or double root.
- If \( b^2 - 4ac < 0 \), the roots are complex and not real.
Real Roots
Real roots are solutions to a quadratic equation where the values satisfy the equation when substituted back. They are found using the quadratic formula or other methods only when the discriminant \( b^2 - 4ac \) is zero or positive.
In our example, the discriminant is calculated to be \( 1 \), which is greater than zero, indicating the presence of two distinct real roots.
To extract these roots from the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \), you solve:
In our example, the discriminant is calculated to be \( 1 \), which is greater than zero, indicating the presence of two distinct real roots.
To extract these roots from the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \), you solve:
- The root \( x_1 \) derived from the \( + \) sign.
- The root \( x_2 \) derived from the \( - \) sign.
Standard Form of a Quadratic Equation
The standard form of a quadratic equation is \( ax^2 + bx + c = 0 \). This form is pivotal because it sets the stage for various solution methods, including the quadratic formula.
To effectively use the quadratic formula, a quadratic equation must be written in this standard form, where
To effectively use the quadratic formula, a quadratic equation must be written in this standard form, where
- \( a \) is the coefficient of \( x^2 \), known as the leading coefficient, and cannot be zero.
- \( b \) is the coefficient of \( x \), the linear term.
- \( c \) is the constant term.