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Solve the following system of equations by the substitution method:

[tex]\[
\begin{cases}
2x - 5 = y \\
\frac{x}{4} + \frac{y}{3} = 2
\end{cases}
\][/tex]

[tex]\[
(x, y) = \square
\][/tex]


Sagot :

Let's solve the given system of equations using the substitution method. The system of equations is:

[tex]\[ \left\{ \begin{array}{l} 2x - 5 = y \\ \frac{x}{4} + \frac{y}{3} = 2 \\ \end{array}\right. \][/tex]

Step 1: Solve the first equation for [tex]\( y \)[/tex].

[tex]\[ 2x - 5 = y \][/tex]

Rewriting this, we get:

[tex]\[ y = 2x - 5 \][/tex]

Step 2: Substitute the expression for [tex]\( y \)[/tex] from the first equation into the second equation.

The second equation is:

[tex]\[ \frac{x}{4} + \frac{y}{3} = 2 \][/tex]

Substitute [tex]\( y = 2x - 5 \)[/tex] into the second equation:

[tex]\[ \frac{x}{4} + \frac{2x - 5}{3} = 2 \][/tex]

Step 3: Solve for [tex]\( x \)[/tex].

To solve the equation, first clear the fractions by finding a common denominator. The common denominator for 4 and 3 is 12. So, we write:

[tex]\[ \frac{3x}{12} + \frac{4(2x - 5)}{12} = 2 \][/tex]

Simplify the numerators:

[tex]\[ \frac{3x + 8x - 20}{12} = 2 \][/tex]
[tex]\[ \frac{11x - 20}{12} = 2 \][/tex]

To get rid of the denominator, multiply both sides by 12:

[tex]\[ 11x - 20 = 24 \][/tex]

Solving for [tex]\( x \)[/tex], we get:

[tex]\[ 11x = 44 \][/tex]

[tex]\[ x = 4 \][/tex]

Step 4: Substitute [tex]\( x = 4 \)[/tex] back into the expression for [tex]\( y \)[/tex].

The expression for [tex]\( y \)[/tex] from Step 1 is:

[tex]\[ y = 2x - 5 \][/tex]

Substitute [tex]\( x = 4 \)[/tex]:

[tex]\[ y = 2(4) - 5 \][/tex]
[tex]\[ y = 8 - 5 \][/tex]
[tex]\[ y = 3 \][/tex]

So, the solution to the system of equations is:

[tex]\[ (x, y) = (4, 3) \][/tex]