Chapter 1: Problem 35
Find all real solutions of the equation. \(3 x^{2}+6 x-5=0\)
Short Answer
Expert verified
The real solutions are \(x = -1 + \frac{2\sqrt{6}}{3}\) and \(x = -1 - \frac{2\sqrt{6}}{3}\).
Step by step solution
01
Identify the Quadratic Equation
The given equation is a quadratic equation of the standard form, \(ax^2 + bx + c = 0\), where \(a = 3\), \(b = 6\), and \(c = -5\).
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 to find \(D = 6^2 - 4 \times 3 \times (-5) = 36 + 60 = 96\).
03
Check the Nature of the Roots
Since the discriminant \(D = 96\) is greater than zero, the quadratic equation has two distinct real solutions.
04
Use the Quadratic Formula
The solutions of the quadratic equation are given by the quadratic formula: \(x = \frac{-b \pm \sqrt{D}}{2a}\). Substitute the values we have: \(x = \frac{-6 \pm \sqrt{96}}{6}\).
05
Simplify the Square Root
First simplify \(\sqrt{96}\). Since \(96 = 16 \times 6\), we can write \(\sqrt{96} = \sqrt{16 \times 6} = \sqrt{16} \times \sqrt{6} = 4\sqrt{6}\).
06
Solve for the Roots
Plug \(\sqrt{96} = 4\sqrt{6}\) into the quadratic formula: \(x = \frac{-6 \pm 4\sqrt{6}}{6}\). Simplify to get the solutions: \(x = \frac{-6 + 4\sqrt{6}}{6}\) and \(x = \frac{-6 - 4\sqrt{6}}{6}\). Further simplification gives \(x = -1 + \frac{2\sqrt{6}}{3}\) and \(x = -1 - \frac{2\sqrt{6}}{3}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Discriminant
The discriminant is a key component when solving quadratic equations, as it helps determine the nature of the roots. A quadratic equation takes the form \(ax^2 + bx + c = 0\). The discriminant \(D\) for this equation is calculated as \(D = b^2 - 4ac\).
The value of the discriminant tells us about the potential solutions:
The value of the discriminant tells us about the potential solutions:
- If \(D > 0\), there are two distinct real roots.
- If \(D = 0\), there is exactly one real root, sometimes referred to as a double root.
- If \(D < 0\), there are no real roots, but two complex roots instead.
Solutions of a Quadratic Equation
Finding the solutions of a quadratic equation means identifying the values of \(x\) that satisfy the equation \(ax^2 + bx + c = 0\).
Once you compute the discriminant, it guides you on how the solutions will look:
Once you compute the discriminant, it guides you on how the solutions will look:
- With two distinct real solutions (when \(D > 0\)), you know both solutions will be different real numbers.
- If there is exactly one real solution (\(D = 0\)), the equation results in a perfect square trinomial.
- For no real solutions (\(D < 0\)), solutions turn out to be complex numbers.
Quadratic Formula
The quadratic formula is a trustworthy method to find the solutions of any quadratic equation of the form \(ax^2 + bx + c = 0\).
The formula is given by:\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]This clever formula gives both potential solutions at once:
This solution approach is particularly useful when factoring is difficult or impossible, reinforcing why the quadratic formula is an essential tool in algebra.
The formula is given by:\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]This clever formula gives both potential solutions at once:
- \(\frac{-b + \sqrt{b^2 - 4ac}}{2a}\)
- \(\frac{-b - \sqrt{b^2 - 4ac}}{2a}\)
This solution approach is particularly useful when factoring is difficult or impossible, reinforcing why the quadratic formula is an essential tool in algebra.