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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
2장, 문제 91

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.) See Example 9.
8x272=08x^2 - 72 = 0

검증된 단계별 안내
1
Identify the coefficients of the quadratic equation in the standard form \(ax^2 + bx + c = 0\). For the equation \(8x^2 - 72 = 0\), note that \(a = 8\), \(b = 0\), and \(c = -72\).
Recall the formula for the discriminant: \(\Delta = b^2 - 4ac\). This value helps determine the nature and number of solutions of the quadratic equation.
Substitute the values of \(a\), \(b\), and \(c\) into the discriminant formula: \(\Delta = 0^2 - 4 \times 8 \times (-72)\).
Simplify the expression for the discriminant to find its value (do not calculate the final number, just set up the expression).
Use the value of the discriminant to determine the number and type of solutions: if \(\Delta > 0\), there are two distinct real solutions; if \(\Delta = 0\), there is one real solution; if \(\Delta < 0\), there are two nonreal complex solutions. Also, if \(\Delta\) is a perfect square, the solutions are rational; otherwise, they are irrational.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Discriminant of a Quadratic Equation

The discriminant is a value calculated from the coefficients of a quadratic equation ax² + bx + c = 0, given by the formula Δ = b² - 4ac. It helps determine the nature and number of solutions without solving the equation.
추천 영상:
04:11
The Discriminant

Number and Nature of Solutions Based on the Discriminant

The discriminant indicates the number and type of roots: if Δ > 0, there are two distinct real solutions; if Δ = 0, there is one real repeated solution; if Δ < 0, there are two nonreal complex solutions.
추천 영상:
4:47
The Number e

Rational vs. Irrational Solutions

When the discriminant is a perfect square and positive, the solutions are rational numbers. If the discriminant is positive but not a perfect square, the solutions are irrational. This distinction helps classify the exact nature of the roots.
추천 영상:
05:56
Introduction to Rational Equations