Chapter 3: Problem 39
Use the quadratic formula to find exact solutions. $$5 m^{2}+3 m=2$$
Short Answer
Expert verified
The solutions are \(m = 0.4\) and \(m = -1\).
Step by step solution
01
- Write down the quadratic formula
The quadratic formula is given by \[ m = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
02
- Identify coefficients a, b, and c
Rewrite the equation in the standard form \[ 5m^2 + 3m - 2 = 0 \]. Here, \(a = 5\), \(b = 3\), and \(c = -2\).
03
- Substitute coefficients into the quadratic formula
Substitute \(a = 5\), \(b = 3\), and \(c = -2\) into the quadratic formula: \[ m = \frac{-3 \pm \sqrt{3^2 - 4(5)(-2)}}{2(5)} \]
04
- Simplify under the square root
Calculate the discriminant: \[ 3^2 - 4(5)(-2) = 9 + 40 = 49 \]. Now the equation becomes \[ m = \frac{-3 \pm \sqrt{49}}{10} \]
05
- Solve for both solutions
Since \( \sqrt{49} = 7 \), the equation becomes \[ m = \frac{-3 \pm 7}{10} \]. This results in two solutions: \[ m = \frac{-3 + 7}{10} = \frac{4}{10} = 0.4 \] and \[ m = \frac{-3 - 7}{10} = \frac{-10}{10} = -1 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
solving quadratic equations
Quadratic equations are polynomial equations of the form \[ ax^2 + bx + c = 0 \], where \( a \), \( b \), and \( c \) are constants, and \( x \) is the variable. To solve a quadratic equation, you need to find values of \( x \) that make the equation true. One of the most reliable methods for solving these equations is the quadratic formula. The quadratic formula is given by:
\[ x = \frac{-b \, \pm \, \sqrt{b^2 - 4ac}}{2a} \]
Here, \( a \), \( b \), and \( c \) are the coefficients from the quadratic equation.
Follow these steps to solve using the quadratic formula:
\[ x = \frac{-b \, \pm \, \sqrt{b^2 - 4ac}}{2a} \]
Here, \( a \), \( b \), and \( c \) are the coefficients from the quadratic equation.
Follow these steps to solve using the quadratic formula:
- Identify the coefficients \( a \), \( b \), and \( c \) from the equation.
- Insert these values into the quadratic formula.
- Calculate the discriminant (the value under the square root sign).
- Solve for both possible answers by using \( + \) and \( - \) in the formula.
discriminant
The discriminant is an important part of the quadratic formula. It is represented as \( b^2 - 4ac \). The value of the discriminant helps us understand the nature of the roots of the quadratic equation:
* When the discriminant is positive (\( b^2 - 4ac > 0 \)), the quadratic equation has two distinct real solutions.
* When the discriminant is zero (\( b^2 - 4ac = 0 \)), the quadratic equation has exactly one real solution. This means the parabola touches the x-axis at one point.
* When the discriminant is negative (\( b^2 - 4ac < 0 \)), the quadratic equation has no real solutions. Instead, it has two complex solutions.
In the given problem, the equation is \( 5m^2 + 3m - 2 = 0 \), and we found that the discriminant is 49 (which is positive). Therefore, there are two distinct real solutions.
* When the discriminant is positive (\( b^2 - 4ac > 0 \)), the quadratic equation has two distinct real solutions.
* When the discriminant is zero (\( b^2 - 4ac = 0 \)), the quadratic equation has exactly one real solution. This means the parabola touches the x-axis at one point.
* When the discriminant is negative (\( b^2 - 4ac < 0 \)), the quadratic equation has no real solutions. Instead, it has two complex solutions.
In the given problem, the equation is \( 5m^2 + 3m - 2 = 0 \), and we found that the discriminant is 49 (which is positive). Therefore, there are two distinct real solutions.
coefficients in quadratic equations
Coefficients in a quadratic equation are the numbers in front of the variables in the standard form \( ax^2 + bx + c = 0 \). These coefficients (\( a \), \( b \), and \( c \)) determine the shape and position of the parabola represented by the equation.
Here is what each coefficient represents:
Here is what each coefficient represents:
- \( a \) (the coefficient of \( x^2 \)) determines the direction and width of the parabola. If \( a \) is positive, the parabola opens upwards. If \( a \) is negative, it opens downwards. A larger absolute value of \( a \) makes the parabola narrower, while a smaller absolute value makes it wider.
- \( b \) (the coefficient of \( x \)) affects the position of the vertex of the parabola along the x-axis.
- \( c \) (the constant term) moves the parabola up or down along the y-axis.