Chapter 9: Problem 29
Use the quadratic formula to solve the following. $$-x_{2}+16 x-62=0$$
Short Answer
Expert verified
The solutions are \(x = 8 - \sqrt{2}\) and \(x = 8 + \sqrt{2}\).
Step by step solution
01
Identify coefficients
The quadratic equation is given by \[-x^2 + 16x - 62 = 0.\]We need to identify the coefficients corresponding to the general quadratic equation format \[ax^2 + bx + c = 0.\]In this equation, they are:- \(a = -1\) (the coefficient of \(x^2\)),- \(b = 16\) (the coefficient of \(x\)),- \(c = -62\) (the constant term).
02
Write down the quadratic formula
The quadratic formula to solve \(ax^2 + bx + c = 0\) is given by:\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}.\]We will use this formula to find the values of \(x\).
03
Calculate the discriminant
The discriminant \(D\) is calculated as:\[D = b^2 - 4ac.\]Using the values identified:\[D = 16^2 - 4(-1)(-62) = 256 - 248 = 8.\]The discriminant helps determine the nature and number of the roots.
04
Substitute into the quadratic formula
Now, substitute the values of \(a\), \(b\), and \(D\) into the quadratic formula:\[x = \frac{-16 \pm \sqrt{8}}{-2}.\]
05
Simplify the roots
First, simplify \(\sqrt{8}\), which can be written as \(2\sqrt{2}\). Thus the equation becomes:\[x = \frac{-16 \pm 2\sqrt{2}}{-2}.\]Break this expression into two solutions:1. \(x_1 = \frac{-16 + 2\sqrt{2}}{-2} = 8 - \sqrt{2}\),2. \(x_2 = \frac{-16 - 2\sqrt{2}}{-2} = 8 + \sqrt{2}\).
06
Present the solutions
The solutions to the quadratic equation are \[x = 8 - \sqrt{2}\] and \[x = 8 + \sqrt{2}.\]These are the two possible values of \(x\) that satisfy the original equation.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equation
A quadratic equation is a type of polynomial equation of degree two. It typically takes the form \( ax^2 + bx + c = 0 \), where \(a\), \(b\), and \(c\) are constants, and "\(a\)" should not be zero since that term gives the equation its quadratic nature. In this context:
Understanding the basic structure of a quadratic equation is crucial because it allows you to apply these solutions. In our exercise, the equation is \(-x^2 + 16x - 62 = 0\), which is correctly identified with coefficients: \(a = -1\), \(b = 16\), and \(c = -62\). Knowing these helps us plug into the quadratic formula effectively.
- \(a\) is the coefficient of \(x^2\).
- \(b\) is the coefficient of \(x\).
- \(c\) is the constant term.
Understanding the basic structure of a quadratic equation is crucial because it allows you to apply these solutions. In our exercise, the equation is \(-x^2 + 16x - 62 = 0\), which is correctly identified with coefficients: \(a = -1\), \(b = 16\), and \(c = -62\). Knowing these helps us plug into the quadratic formula effectively.
Discriminant
The discriminant is a significant component in solving quadratic equations, as it provides valuable information regarding the nature and number of solutions. It is part of the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \) and is denoted by \(D = b^2 - 4ac \).
Here's what the discriminant tells us:
Here's what the discriminant tells us:
- If \(D > 0\), the equation has two distinct real roots.
- If \(D = 0\), there's exactly one real root, meaning the roots are equal.
- If \(D < 0\), the equation has no real roots, but two complex ones.
Roots of Equations
The roots of a quadratic equation are the solutions for \(x\) that satisfy the equation. Using the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \), we find the values of \(x\) where the quadratic expression equals zero. In simpler terms, they are the x-values where the graph of the quadratic intersects the x-axis.
After calculating the discriminant, the next step is to substitute it into the quadratic formula alongside the coefficients. For our specific example with a discriminant of 8:
After calculating the discriminant, the next step is to substitute it into the quadratic formula alongside the coefficients. For our specific example with a discriminant of 8:
- The equation inside the square root becomes \( \sqrt{8} \), which simplifies to \( 2\sqrt{2} \).
- The formula then becomes \( x = \frac{-16 \pm 2\sqrt{2}}{-2} \), yielding two solutions:
- \(x_1 = 8 - \sqrt{2}\)
- \(x_2 = 8 + \sqrt{2}\)