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A variable needs to be eliminated to solve the system of equations below. Choose the correct first step.

{:[3x+6y=45],[3x-7y=-46]:}
Add to eliminate 
x.
Subtract to eliminate 
x.
Subtract to eliminate 
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Add to eliminate 
y.

A variable needs to be eliminated to solve the system of equations below. Choose the correct first step.\newline3x+6y=453x7y=46 \begin{array}{l} 3 x+6 y=45 \\ 3 x-7 y=-46 \end{array} \newlineAdd to eliminate x \mathbf{x} .\newlineSubtract to eliminate x \mathbf{x} .\newlineSubtract to eliminate y \mathbf{y} .\newlineAdd to eliminate y \mathbf{y} .

Full solution

Q. A variable needs to be eliminated to solve the system of equations below. Choose the correct first step.\newline3x+6y=453x7y=46 \begin{array}{l} 3 x+6 y=45 \\ 3 x-7 y=-46 \end{array} \newlineAdd to eliminate x \mathbf{x} .\newlineSubtract to eliminate x \mathbf{x} .\newlineSubtract to eliminate y \mathbf{y} .\newlineAdd to eliminate y \mathbf{y} .
  1. Analyze Variables: Analyze the system of equations to determine which variable can be eliminated with the least amount of work.\newlineWe have the system:\newline\begin{cases}3x+6y=45\3x-7y=-46\end{cases}\newlineTo eliminate a variable, we look for coefficients that are the same or opposites. Here, the coefficients of xx in both equations are the same (33 and 33).
  2. Elimination Operation: Decide on the operation to use for elimination.\newlineSince the coefficients of xx are the same, we can subtract one equation from the other to eliminate xx.
  3. Check Elimination: Perform a quick check to ensure that subtraction will indeed eliminate the variable xx.
    (3x+6y)(3x7y)=45(46)(3x + 6y) - (3x - 7y) = 45 - (-46)
    3x3x+6y+7y=45+463x - 3x + 6y + 7y = 45 + 46
    0x+13y=910x + 13y = 91
    This confirms that subtracting the two equations will eliminate xx.