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Find the solution of the system of equations. \[ \begin{array}{c}8 x+14 y=2 \\ -3 x-7 y=8\end{array} \]

Ask by Hammond Bryant. in the United States
Jan 24,2025

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Tutor-Verified Answer

Answer

The solution is \( x = 9 \) and \( y = -5 \).

Solution

To solve the system of equations: \[ \begin{cases} 8x + 14y = 2 \quad \text{(1)} \\ -3x - 7y = 8 \quad \text{(2)} \end{cases} \] **Step 1: Elimination** Notice that equation (2) can be multiplied by 2 to make the coefficients of \( y \) in both equations opposites: \[ -3x - 7y = 8 \quad \times 2 \implies -6x - 14y = 16 \quad \text{(3)} \] Now, add equation (1) and equation (3): \[ 8x + 14y + (-6x - 14y) = 2 + 16 \\ (8x - 6x) + (14y - 14y) = 18 \\ 2x = 18 \\ x = 9 \] **Step 2: Substitute \( x \) into one of the original equations** Substitute \( x = 9 \) into equation (2): \[ -3(9) - 7y = 8 \\ -27 - 7y = 8 \\ -7y = 35 \\ y = -5 \] **Solution:** \[ x = 9 \quad \text{and} \quad y = -5 \] **Answer:** The solution is x = 9 and y = –5.

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The Deep Dive

To solve the system of equations: \[ \begin{array}{c} 8x + 14y = 2 \quad (1) \\ -3x - 7y = 8 \quad (2) \end{array} \] We can use the elimination or substitution method. Here, let's use the elimination method. First, we can manipulate the equations to align the coefficients for elimination. Multiply equation (2) by 2 so that the coefficients of \(y\) match: \[ -6x - 14y = 16 \quad (3) \] Now, we have the transformed system: \[ \begin{array}{c} 8x + 14y = 2 \quad (1) \\ -6x - 14y = 16 \quad (3) \end{array} \] Now, we can add equations (1) and (3): \[ (8x + 14y) + (-6x - 14y) = 2 + 16 \] This simplifies to: \[ 2x = 18 \] Dividing both sides by 2 gives: \[ x = 9 \] Now substitute \(x = 9\) back into equation (1) to find \(y\): \[ 8(9) + 14y = 2 \] This simplifies to: \[ 72 + 14y = 2 \] Subtract 72 from both sides: \[ 14y = 2 - 72 \] \[ 14y = -70 \] Now divide by 14: \[ y = -5 \] Thus, the solution to the system of equations is: \[ (x, y) = (9, -5) \]

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