Chapter 8: Problem 8
Use the quadratic formula to solve each equation. (All solutions for these equations are real numbers.) $$ 8 x^{2}+10 x-3=0 $$
Short Answer
Expert verified
\( \frac{1}{4} \) and \( -\frac{3}{2} \)
Step by step solution
01
Identify coefficients
For the quadratic equation in standard form, identify the coefficients. The standard form is given by: \[ ax^2 + bx + c = 0 \] In this equation, \( a = 8 \), \( b = 10 \), and \( c = -3 \).
02
Write the quadratic formula
The quadratic formula to solve an equation of the form \( ax^2 + bx + c = 0 \) is: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
03
Calculate the discriminant
Calculate the discriminant which is the expression under the square root in the quadratic formula: \[ b^2 - 4ac \] Substituting the coefficients: \[ (10)^2 - 4(8)(-3) = 100 + 96 = 196 \]
04
Compute the square root of the discriminant
Find the square root of the discriminant: \[ \sqrt{196} = 14 \]
05
Apply the quadratic formula
Substitute the values of \( b \), \( \sqrt{b^2 - 4ac} \), and \( a \) back into the quadratic formula: \[ x = \frac{-10 \pm 14}{2(8)} \]
06
Calculate the two solutions
Solve for the two possible values of \( x \): \[ x = \frac{-10 + 14}{16} = \frac{4}{16} = \frac{1}{4} \] and \[ x = \frac{-10 - 14}{16} = \frac{-24}{16} = -\frac{3}{2} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equations
Quadratic equations are fundamental in algebra and describe a wide range of phenomena. A quadratic equation is any equation that can be written in the form \[ ax^2 + bx + c = 0 \] where:
- \(a\) is the coefficient of the squared term \(x^2\)
- \(b\) is the coefficient of the linear term \(x\)
- \(c\) is the constant term
Discriminant
The discriminant is a key part of the quadratic formula and helps determine the nature of the solutions. The discriminant is the term under the square root in the quadratic formula: \[ b^2 - 4ac \] Depending on the value of the discriminant, we can determine the types of solutions to our quadratic equation:
- If \( b^2 - 4ac > 0 \), there are two distinct real solutions.
- If \( b^2 - 4ac = 0 \), there is one real solution (a repeated root).
- If \( b^2 - 4ac < 0 \), there are no real solutions; instead, the solutions are complex or imaginary.
Real Number Solutions
Real number solutions are the points where the quadratic equation crosses the x-axis on a graph. Solving for these involves using the quadratic formula \[ x = \frac{-b \,\pm \sqrt{b^2 - 4ac}}{2a} \] For the specific example:
- Our coefficients were \(a = 8\), \( b = 10 \), and \( c = -3 \).
- The discriminant was determined to be \( 196 \), a positive number, indicating two distinct real solutions.
- Substituting back into the quadratic formula gave two solutions: \( x = \frac{1}{4} \) and \( x = -\frac{3}{2} \).