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Ch. 5 - Systems of Equations and Inequalities
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Non è quello che usi tu?Cambia libro di testo
Capitolo 6, Problema 21

In Exercises 19–28, solve each system by the addition method. {x2−4y2=−73x2+y2=31\(\begin{cases}\) x^2 - 4y^2 = -7 \\ 3x^2 + y^2 = 31 \(\end{cases}\)

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1
Identify the system of equations: \(x^2 - 4y^2 = -7\) \(3x^2 + y^2 = 31\)
To use the addition method, first align the equations so that adding or subtracting them will eliminate one variable. Notice the variables are \(x^2\) and \(y^2\), so treat \(x^2\) and \(y^2\) as separate terms.
Multiply the second equation by 4 to match the coefficient of \(y^2\) in the first equation: \(4(3x^2 + y^2) = 4(31)\) which gives \(12x^2 + 4y^2 = 124\)
Now add the first equation and the new equation: \((x^2 - 4y^2) + (12x^2 + 4y^2) = -7 + 124\) Simplify the left side to eliminate \(y^2\) terms and combine like terms.
Solve the resulting equation for \(x^2\), then substitute this value back into one of the original equations to find \(y^2\). Finally, take square roots to find \(x\) and \(y\) values, remembering to consider both positive and negative roots.

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