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Which of these strategies would eliminate a variable in the system of equations?

{[-7x+2y=5],[3x-5y=-5]:}
Choose 2 answers:
A Multiply the top equation by 3 , multiply the bottom equation by 7 , then add the equations.
B] Add the equations.
c Multiply the top equation by 5 , multiply the bottom equation by 2 , then add the equations.

Which of these strategies would eliminate a variable in the system of equations?\newline{7x+2y=53x5y=5 \left\{\begin{array}{l} -7 x+2 y=5 \\ 3 x-5 y=-5 \end{array}\right. \newlineChoose 22 answers:\newline(A) Multiply the top equation by 33 , multiply the bottom equation by 77 , then add the equations.\newline(B) Add the equations.\newline(C) Multiply the top equation by 55 , multiply the bottom equation by 22 , then add the equations.

Full solution

Q. Which of these strategies would eliminate a variable in the system of equations?\newline{7x+2y=53x5y=5 \left\{\begin{array}{l} -7 x+2 y=5 \\ 3 x-5 y=-5 \end{array}\right. \newlineChoose 22 answers:\newline(A) Multiply the top equation by 33 , multiply the bottom equation by 77 , then add the equations.\newline(B) Add the equations.\newline(C) Multiply the top equation by 55 , multiply the bottom equation by 22 , then add the equations.
  1. Analyze system of equations: Analyze the given system of equations to determine which variable can be eliminated using the given strategies.\newlineThe system of equations is:\newline7x+2y=5-7x + 2y = 5\newline3x5y=53x - 5y = -5
  2. Strategy A: Multiply and add equations: Consider strategy A: Multiply the top equation by 33, multiply the bottom equation by 77, then add the equations.\newlineMultiplying the top equation by 33 gives us:\newline21x+6y=15-21x + 6y = 15\newlineMultiplying the bottom equation by 77 gives us:\newline21x35y=3521x - 35y = -35
  3. Check elimination of variable x: Add the equations from strategy A to see if a variable is eliminated.\newline(21-21x + 66y) + (2121x - 3535y) = 1515 - 3535\newlineThe x terms cancel out, and we are left with:\newline66y - 3535y = 20-20\newline29-29y = 20-20\newlineThis strategy eliminates the variable x.
  4. Strategy B: Add equations: Consider strategy B: Add the equations without any multiplication.\newline(7x+2y)+(3x5y)=55(-7x + 2y) + (3x - 5y) = 5 - 5\newline7x+3x+2y5y=0-7x + 3x + 2y - 5y = 0\newline4x3y=0-4x - 3y = 0\newlineThis strategy does not eliminate any variable, as both xx and yy are still present in the equation.
  5. No elimination of variables: Consider strategy C: Multiply the top equation by 55, multiply the bottom equation by 22, then add the equations.\newlineMultiplying the top equation by 55 gives us:\newline35x+10y=25-35x + 10y = 25\newlineMultiplying the bottom equation by 22 gives us:\newline6x10y=106x - 10y = -10
  6. Strategy C: Multiply and add equations: Add the equations from strategy C to see if a variable is eliminated.\newline(35x+10y)+(6x10y)=2510(-35x + 10y) + (6x - 10y) = 25 - 10\newlineThe y terms cancel out, and we are left with:\newline35x+6x=15-35x + 6x = 15\newline29x=15-29x = 15\newlineThis strategy eliminates the variable y.

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