Chapter 10: Problem 129
Solve by using the Quadratic Formula. \(2 x^{2}+12 x-3=0\)
Short Answer
Expert verified
The solutions are \( x = -3 + \frac{\sqrt{42}}{2} \) and \( x = -3 - \frac{\sqrt{42}}{2} \).
Step by step solution
01
Identify coefficients
First, identify the coefficients for the quadratic equation in the form of \( ax^{2} + bx + c = 0 \). Here, \( a = 2 \), \( b = 12 \), and \( c = -3 \).
02
Write the Quadratic Formula
The Quadratic Formula is given by \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \).
03
Substitute the values into the formula
Substitute \( a = 2 \), \( b = 12 \), and \( c = -3 \) into the formula: \( x = \frac{-12 \pm \sqrt{12^2 - 4 \cdot 2 \cdot (-3)}}{2 \cdot 2} \).
04
Simplify inside the square root
Calculate the value inside the square root: \( 12^2 - 4 \cdot 2 \cdot (-3) = 144 + 24 = 168 \). So, the formula becomes: \( x = \frac{-12 \pm \sqrt{168}}{4} \).
05
Simplify the square root
Simplify \( \sqrt{168} \). \( \sqrt{168} = \sqrt{4 \cdot 42} = \sqrt{4} \cdot \sqrt{42} = 2 \sqrt{42} \).
06
Final simplification
Substitute \( \sqrt{168} = 2 \sqrt{42} \) back into the formula: \( x = \frac{-12 \pm 2 \sqrt{42}}{4} \). Simplify further: \( x = \frac{-12 + 2 \sqrt{42}}{4} = \frac{-12 - 2 \sqrt{42}}{4} \).
07
Express in simplest form
Divide both terms in the numerator by 4: \( x = \frac{-12}{4} + \frac{2 \sqrt{42}}{4} = -3 + \frac{\sqrt{42}}{2} \) and \( x = \frac{-12}{4} - \frac{2 \sqrt{42}}{4} = -3 - \frac{\sqrt{42}}{2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
solving quadratic equations
A quadratic equation is an equation of the form \[ax^{2} + bx + c = 0\]To find the solutions of a quadratic equation, you can use the Quadratic Formula:\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]In this formula,
- a is the coefficient of the term \(x^{2}\)
- b is the coefficient of the term \(x\)
- c is the constant term
simplifying square roots
When solving quadratic equations, you might need to simplify square roots. For example, \(\sqrt{168}\). To simplify a square root:
- Factor the number inside the square root into its prime factors.
- Look for perfect square factors.
- Rewrite the square root as a product of square roots.
- Simplify the square root of perfect squares.
coefficients in algebra
Coefficients are the numerical factors in the terms of an equation. In the quadratic equation \(2x^{2}+12x-3=0\),
- The coefficient of \(x^{2}\) is 2.
- The coefficient of \(x\) is 12.
- The constant term is -3.