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Math

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PROBLEM

Complete the sentence below by replacing ? with an appropriate value.
Using Cramer's Rule, the value of xx that satisfies the system of equations {2x+3y=5x4y=3\left\{\begin{array}{l}2 x+3 y=5 \\ x-4 y=-3\end{array}\right. is x=?2314x=\frac{?}{\left|\begin{array}{rr}2 & 3 \\ 1 & -4\end{array}\right|}

STEP 1

What is this asking?
We need to find the numerator of the fraction when solving for xx in a system of two equations using Cramer's Rule.
Watch out!
Don't forget to use the correct coefficients when setting up the determinant for the numerator!

STEP 2

1. Set up the system of equations.
2. Calculate the determinant for the numerator.

STEP 3

Alright, let's begin by clearly writing out our system of equations:
2x+3y=5x4y=3\begin{array}{l} 2x + 3y = 5 \\ x - 4y = -3 \end{array}

STEP 4

Remember, Cramer's rule helps us solve for xx and yy using determinants.
It's like a shortcut to find the solutions!

STEP 5

When using Cramer's Rule to solve for xx, the numerator of the xx solution is a special determinant.
We replace the coefficients of xx in the system of equations with the constant terms.

STEP 6

The coefficients of xx are 2\mathbf{2} and 1\mathbf{1}.
The constant terms are 5\mathbf{5} and 3\mathbf{-3}.
So, we replace the xx coefficients with the constant terms.
The coefficients of yy remain unchanged.

STEP 7

This gives us the determinant:
5334\begin{vmatrix} 5 & 3 \\ -3 & -4 \end{vmatrix}

STEP 8

Now, let's calculate this determinant!
Remember, it's the product of the main diagonal minus the product of the off-diagonal.
(5(4))(3(3))(\mathbf{5} \cdot (\mathbf{-4})) - (3 \cdot (\mathbf{-3})) 20(9)\mathbf{-20} - (\mathbf{-9})

STEP 9

Remember, subtracting a negative number is the same as adding its positive counterpart.
So, we have:
20+9=11\mathbf{-20} + \mathbf{9} = \mathbf{-11} So, the determinant of the numerator is 11\mathbf{-11}!

SOLUTION

The value of xx that satisfies the system of equations is x=112314 x = \frac{\mathbf{-11}}{\begin{vmatrix} 2 & 3 \\ 1 & -4 \end{vmatrix}} .
Therefore, the missing value is 11\mathbf{-11}.

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