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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 2, Problem 83

Evaluate the discriminant for each equation. Then use it to determine the number of distinct solutions, and tell whether they are rational, irrational, or nonreal complex numbers. (Do not solve the equation.) x2 - 8x + 16 = 0

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1
Identify the coefficients of the quadratic equation in the form \(ax^2 + bx + c = 0\). Here, \(a = 1\), \(b = -8\), and \(c = 16\).
Recall the formula for the discriminant: \(\Delta = b^2 - 4ac\).
Substitute the values of \(a\), \(b\), and \(c\) into the discriminant formula: \(\Delta = (-8)^2 - 4 \times 1 \times 16\).
Simplify the expression to find the value of the discriminant (do not calculate the final number, just set up the expression).
Use the value of the discriminant to determine the nature of the roots: if \(\Delta > 0\) and a perfect square, roots are rational and distinct; if \(\Delta > 0\) but not a perfect square, roots are irrational and distinct; if \(\Delta = 0\), roots are real and equal (rational); if \(\Delta < 0\), roots are nonreal complex numbers.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Discriminant of a Quadratic Equation

The discriminant is a value calculated from the coefficients of a quadratic equation ax² + bx + c = 0, given by b² - 4ac. It helps determine the nature and number of solutions without solving the equation.
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Number and Nature of Solutions Based on the Discriminant

If the discriminant is positive, there are two distinct real solutions; if zero, one real repeated solution; if negative, two nonreal complex solutions. This classification guides understanding the roots' behavior.
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Rational vs. Irrational Solutions

When the discriminant is a perfect square, the solutions are rational numbers; if positive but not a perfect square, the solutions are irrational. This distinction helps describe the exact type of real roots.
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