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Sagot :
To solve the given system by elimination, let's go through the process step-by-step:
1. Write down the system of equations:
[tex]\[ \begin{cases} 2x - 3y = 19 \quad \text{(Equation 1)} \\ 5x + 4y = -10 \quad \text{(Equation 2)} \end{cases} \][/tex]
2. Eliminate one variable by adding or subtracting the equations. To do this, we need to make the coefficients of one variable (either [tex]\( x \)[/tex] or [tex]\( y \)[/tex]) equal in both equations. Let's eliminate [tex]\( y \)[/tex].
3. Find the common multiple of the coefficients of [tex]\( y \)[/tex]: The coefficients of [tex]\( y \)[/tex] are [tex]\(-3\)[/tex] in Equation 1 and [tex]\(4\)[/tex] in Equation 2. The least common multiple of 3 and 4 is 12. Thus, we will multiply the entire Equation 1 by [tex]\(4\)[/tex] and the entire Equation 2 by [tex]\(3\)[/tex] so the coefficients of [tex]\( y \)[/tex] become [tex]\( -12 \)[/tex] and [tex]\( 12 \)[/tex] respectively.
[tex]\[ 4 \cdot (2x - 3y) = 4 \cdot 19 \][/tex]
[tex]\[ 3 \cdot (5x + 4y) = 3 \cdot (-10) \][/tex]
This yields:
[tex]\[ 8x - 12y = 76 \quad \text{(Equation 3)} \][/tex]
[tex]\[ 15x + 12y = -30 \quad \text{(Equation 4)} \][/tex]
4. Add Equation 3 and Equation 4 to eliminate [tex]\( y \)[/tex]:
[tex]\[ (8x - 12y) + (15x + 12y) = 76 + (-30) \][/tex]
Simplifying this, we get:
[tex]\[ 23x = 46 \][/tex]
5. Solve for [tex]\( x \)[/tex]:
[tex]\[ x = \frac{46}{23} \][/tex]
[tex]\[ x = 2 \][/tex]
6. Substitute [tex]\( x = 2 \)[/tex] back into one of the original equations to find [tex]\( y \)[/tex]. We will use Equation 1:
[tex]\[ 2(2) - 3y = 19 \][/tex]
Simplifying this, we get:
[tex]\[ 4 - 3y = 19 \][/tex]
[tex]\[ -3y = 19 - 4 \][/tex]
[tex]\[ -3y = 15 \][/tex]
[tex]\[ y = \frac{15}{-3} \][/tex]
[tex]\[ y = -5 \][/tex]
Therefore, the solution to the system of equations is:
[tex]\[ \boxed{(2, -5)} \][/tex]
So, the correct choice is:
A. The solution set is [tex]\(\{ (2, -5) \} \)[/tex].
1. Write down the system of equations:
[tex]\[ \begin{cases} 2x - 3y = 19 \quad \text{(Equation 1)} \\ 5x + 4y = -10 \quad \text{(Equation 2)} \end{cases} \][/tex]
2. Eliminate one variable by adding or subtracting the equations. To do this, we need to make the coefficients of one variable (either [tex]\( x \)[/tex] or [tex]\( y \)[/tex]) equal in both equations. Let's eliminate [tex]\( y \)[/tex].
3. Find the common multiple of the coefficients of [tex]\( y \)[/tex]: The coefficients of [tex]\( y \)[/tex] are [tex]\(-3\)[/tex] in Equation 1 and [tex]\(4\)[/tex] in Equation 2. The least common multiple of 3 and 4 is 12. Thus, we will multiply the entire Equation 1 by [tex]\(4\)[/tex] and the entire Equation 2 by [tex]\(3\)[/tex] so the coefficients of [tex]\( y \)[/tex] become [tex]\( -12 \)[/tex] and [tex]\( 12 \)[/tex] respectively.
[tex]\[ 4 \cdot (2x - 3y) = 4 \cdot 19 \][/tex]
[tex]\[ 3 \cdot (5x + 4y) = 3 \cdot (-10) \][/tex]
This yields:
[tex]\[ 8x - 12y = 76 \quad \text{(Equation 3)} \][/tex]
[tex]\[ 15x + 12y = -30 \quad \text{(Equation 4)} \][/tex]
4. Add Equation 3 and Equation 4 to eliminate [tex]\( y \)[/tex]:
[tex]\[ (8x - 12y) + (15x + 12y) = 76 + (-30) \][/tex]
Simplifying this, we get:
[tex]\[ 23x = 46 \][/tex]
5. Solve for [tex]\( x \)[/tex]:
[tex]\[ x = \frac{46}{23} \][/tex]
[tex]\[ x = 2 \][/tex]
6. Substitute [tex]\( x = 2 \)[/tex] back into one of the original equations to find [tex]\( y \)[/tex]. We will use Equation 1:
[tex]\[ 2(2) - 3y = 19 \][/tex]
Simplifying this, we get:
[tex]\[ 4 - 3y = 19 \][/tex]
[tex]\[ -3y = 19 - 4 \][/tex]
[tex]\[ -3y = 15 \][/tex]
[tex]\[ y = \frac{15}{-3} \][/tex]
[tex]\[ y = -5 \][/tex]
Therefore, the solution to the system of equations is:
[tex]\[ \boxed{(2, -5)} \][/tex]
So, the correct choice is:
A. The solution set is [tex]\(\{ (2, -5) \} \)[/tex].
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