QuestionAugust 26, 2025

Solve the system of equations. x+4y=15 2x-y=-15

Solve the system of equations. x+4y=15 2x-y=-15
Solve the system of equations.
x+4y=15
2x-y=-15

Solution
4.1(293 votes)

Answer

x = -5, y = 5 Explanation 1. Solve for x in terms of y From the first equation, x = 15 - 4y. 2. Substitute x into the second equation Substitute x = 15 - 4y into 2x - y = -15: 2(15 - 4y) - y = -15. 3. Simplify and solve for y 30 - 8y - y = -15 \Rightarrow 30 - 9y = -15 \Rightarrow 9y = 45 \Rightarrow y = 5. 4. Substitute y back to find x Substitute y = 5 into x = 15 - 4y: x = 15 - 4(5) = 15 - 20 = -5.

Explanation

1. Solve for $x$ in terms of $y$<br /> From the first equation, $x = 15 - 4y$.<br />2. Substitute $x$ into the second equation<br /> Substitute $x = 15 - 4y$ into $2x - y = -15$: <br /> $2(15 - 4y) - y = -15$.<br />3. Simplify and solve for $y$<br /> $30 - 8y - y = -15 \Rightarrow 30 - 9y = -15 \Rightarrow 9y = 45 \Rightarrow y = 5$.<br />4. Substitute $y$ back to find $x$<br /> Substitute $y = 5$ into $x = 15 - 4y$: <br /> $x = 15 - 4(5) = 15 - 20 = -5$.
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