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Ch. 5 - Systems of Equations and Inequalities
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 49

In Exercises 47–52, solve each system by the method of your choice. {4x+y=12y=x3+3x2\(\begin{cases}\) -4x + y = 12 \\ y = x^3 + 3x^2 \(\end{cases}\)

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Start with the given system of equations: \(-4x + y = 12\) and \(y = x^3 + 3x^2\).
Since both equations are equal to \(y\), set the right-hand sides equal to each other to eliminate \(y\): \(-4x + y = 12\) implies \(y = 4x + 12\) (by adding \$4x$ to both sides), so set \(4x + 12 = x^3 + 3x^2\).
Rewrite the equation to bring all terms to one side, forming a polynomial equation: \(x^3 + 3x^2 - 4x - 12 = 0\).
Solve the cubic equation \(x^3 + 3x^2 - 4x - 12 = 0\) by factoring or using methods such as the Rational Root Theorem to find possible roots for \(x\).
Once you find the values of \(x\), substitute each back into one of the original equations (for example, \(y = 4x + 12\)) to find the corresponding \(y\) values, giving you the solution pairs \((x, y)\).

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주요 개념

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

Systems of Equations

A system of equations consists of two or more equations with the same variables. The goal is to find values for the variables that satisfy all equations simultaneously. Solutions can be points where the graphs of the equations intersect.
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Introduction to Systems of Linear Equations

Substitution Method

The substitution method involves solving one equation for one variable and then substituting that expression into the other equation. This reduces the system to a single equation with one variable, making it easier to solve.
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Choosing a Method to Solve Quadratics

Solving Nonlinear Equations

When a system includes nonlinear equations, such as cubic or quadratic terms, solving requires careful algebraic manipulation. After substitution, the resulting equation may be polynomial, requiring factoring or other methods to find roots.
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Nonlinear Inequalities