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Ch. 5 - Systems and Matrices
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 67

Use Cramer's rule to solve each system of equations. If D = 0, then use another method to determine the solution set. See Examples 5–7.
5x+4y=105x + 4y = 10
5x+4y=105x + 4y = 10

검증된 단계별 안내
1
Write the system of equations in standard form: \(5x + 4y = 10\) and \(3x - 7y = 6\).
Identify the coefficient matrix and calculate the determinant \(D\): \(D = \begin{vmatrix} 5 & 4 \\ 3 & -7 \end{vmatrix} = (5)(-7) - (4)(3)\).
Calculate the determinant \(D_x\) by replacing the first column of the coefficient matrix with the constants from the right side of the equations: \(D_x = \begin{vmatrix} 10 & 4 \\ 6 & -7 \end{vmatrix} = (10)(-7) - (4)(6)\).
Calculate the determinant \(D_y\) by replacing the second column of the coefficient matrix with the constants: \(D_y = \begin{vmatrix} 5 & 10 \\ 3 & 6 \end{vmatrix} = (5)(6) - (10)(3)\).
Use Cramer's rule to find the solutions for \(x\) and \(y\): \(x = \frac{D_x}{D}\) and \(y = \frac{D_y}{D}\). If \(D = 0\), then use another method such as substitution or elimination to find the solution set.

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주요 개념

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

Cramer's Rule

Cramer's Rule is a method for solving systems of linear equations using determinants. For a system of two equations with two variables, it involves calculating the determinant of the coefficient matrix (D) and determinants of matrices formed by replacing columns with constants. If D ≠ 0, the system has a unique solution found by dividing these determinants.
추천 영상:
6:54
Cramer's Rule - 2 Equations with 2 Unknowns

Determinant of a 2x2 Matrix

The determinant of a 2x2 matrix [[a, b], [c, d]] is calculated as ad - bc. This value helps determine if the system of equations has a unique solution (nonzero determinant) or if it is dependent or inconsistent (zero determinant). It is essential for applying Cramer's Rule.
추천 영상:
4:36
Determinants of 2×2 Matrices

Alternative Methods for Solving Systems When D = 0

If the determinant D equals zero, Cramer's Rule cannot be used because the system may have infinitely many solutions or no solution. In such cases, methods like substitution, elimination, or matrix row reduction are used to analyze the system and find the solution set or determine inconsistency.
추천 영상:
04:03
Choosing a Method to Solve Quadratics