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Solve the following system of linear equations:

[tex]\[
\begin{array}{l}
4x - 5y = 3 \\
3x + 5y = 11
\end{array}
\][/tex]

A. [tex]\((2,1)\)[/tex]
B. [tex]\((0,2)\)[/tex]
C. [tex]\((2,0)\)[/tex]
D. [tex]\((1,2)\)[/tex]


Sagot :

To solve the system of linear equations:

[tex]\[ \begin{cases} 4x - 5y = 3 \\ 3x + 5y = 11 \end{cases} \][/tex]

we will use the method of elimination or substitution.

### Step-by-Step Solution:

#### 1. Write down both equations:
[tex]\[ 4x - 5y = 3 \quad \text{(Equation 1)} \][/tex]
[tex]\[ 3x + 5y = 11 \quad \text{(Equation 2)} \][/tex]

#### 2. Add the two equations to eliminate [tex]\(y\)[/tex]:
[tex]\[ (4x - 5y) + (3x + 5y) = 3 + 11 \][/tex]
This simplifies to:
[tex]\[ (4x + 3x) + (-5y + 5y) = 14 \][/tex]
[tex]\[ 7x = 14 \][/tex]

#### 3. Solve for [tex]\(x\)[/tex]:
[tex]\[ x = \frac{14}{7} = 2 \][/tex]

#### 4. Substitute [tex]\(x = 2\)[/tex] back into one of the original equations to find [tex]\(y\)[/tex]. Let's use Equation 1:
[tex]\[ 4(2) - 5y = 3 \][/tex]
[tex]\[ 8 - 5y = 3 \][/tex]
Subtract 8 from both sides:
[tex]\[ -5y = 3 - 8 \][/tex]
[tex]\[ -5y = -5 \][/tex]
Divide by -5:
[tex]\[ y = 1 \][/tex]

So, the solution to the system of equations is:
[tex]\[ (x, y) = (2, 1) \][/tex]

#### 5. Check the solution in both equations:

Substitute into Equation 1:
[tex]\[ 4(2) - 5(1) = 8 - 5 = 3 \quad \text{Correct} \][/tex]

Substitute into Equation 2:
[tex]\[ 3(2) + 5(1) = 6 + 5 = 11 \quad \text{Correct} \][/tex]

Both checks confirm that the solution is correct.

### Multiple Choice Selection:
The correct solution corresponds to the choice:
[tex]\[ a. (2, 1) \][/tex]

Therefore, the answer is [tex]\( \boxed{1} \)[/tex].