Chapter 9: Problem 40
\(4 v^{2}+5 v-12=0\)
Short Answer
Expert verified
\(v = \frac{-5 \pm \sqrt{217}}{8}\)
Step by step solution
01
Identify the coefficients
The given equation is in the form of a quadratic equation: \(4v^2 + 5v - 12 = 0\). Identify the coefficients: \(a = 4\), \(b = 5\), and \(c = -12\).
02
Calculate the discriminant
The discriminant \(D\) of a quadratic equation \(ax^2 + bx + c = 0\) is given by the formula: \(D = b^2 - 4ac\). Substitute the values of \(a, b,\) and \(c\): \(D = 5^2 - 4(4)(-12) = 25 + 192 = 217\).
03
Apply the quadratic formula
The solutions for the quadratic equation can be found using the quadratic formula: \(v = \frac{-b \pm \sqrt{D}}{2a}\). Since \(D = 217\), \(a = 4\), and \(b = 5\), substitute these values into the formula: \(v = \frac{-5 \pm \sqrt{217}}{8}\).
04
Simplify the solutions
Write the two solutions explicitly: \(v_1 = \frac{-5 + \sqrt{217}}{8}\) and \(v_2 = \frac{-5 - \sqrt{217}}{8}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Coefficients
In a quadratic equation, the coefficients are the numerical values that multiply the variables. A standard quadratic equation is written in the form: \(ax^2 + bx + c = 0\). Here,
- \(a\) is the coefficient of \(x^2\)
- \(b\) is the coefficient of \(x\)
- \(c\) is the constant term
- \(a = 4\)
- \(b = 5\)
- \(c = -12\)
Discriminant
The discriminant \(D\) of a quadratic equation \(ax^2 + bx + c = 0\) helps us determine the nature of the roots without actually solving the equation. It's calculated using the formula: \(D = b^2 - 4ac\)For our given equation with coefficients \(a = 4\), \(b = 5\), and \(c = -12\), the discriminant is calculated as: \[D = 5^2 - 4(4)(-12) = 25 + 192 = 217\]The value of the discriminant can tell us:
- If \(D > 0\), there are two distinct real roots.
- If \(D = 0\), there is one repeated real root.
- If \(D < 0\), there are no real roots, but two complex roots.
Quadratic Formula
The quadratic formula is a way to find the solutions of a quadratic equation \(ax^2 + bx + c = 0\). It is derived from completing the square of the quadratic equation. The formula is: \[x = \frac{-b \pm \sqrt{D}}{2a}\]Where:
- \(D\) is the discriminant
- \(a\), \(b\), and \(c\) are the coefficients
Solving Quadratic Equations
Solving a quadratic equation means finding the values of the variable that make the equation true. Using the quadratic formula, we have: \[v = \frac{-5 \pm \sqrt{217}}{8}\]This can be split into two separate solutions:
- \(v_1 = \frac{-5 + \sqrt{217}}{8}\)
- \(v_2 = \frac{-5 - \sqrt{217}}{8}\)