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Solve the system by substitution.

{:[y=-7x-2],[-2x-2y=40]:}

Solve the system by substitution.\newliney=7x22x2y=40 \begin{aligned} y & =-7 x-2 \\ -2 x-2 y & =40 \end{aligned}

Full solution

Q. Solve the system by substitution.\newliney=7x22x2y=40 \begin{aligned} y & =-7 x-2 \\ -2 x-2 y & =40 \end{aligned}
  1. Identify Equations: First, we need to identify the two equations in the system that we will be working with.\newlineEquation 11: y=7x2y = -7x - 2\newlineEquation 22: 2x2y=40-2x - 2y = 40\newlineWe will use substitution to solve the system, which means we will substitute the expression for yy from Equation 11 into Equation 22.
  2. Substitute yy into Equation 22: Substitute y=7x2y = -7x - 2 from Equation 11 into Equation 22.\newlineEquation 22 becomes: 2x2(7x2)=40-2x - 2(-7x - 2) = 40\newlineNow we need to simplify and solve for xx.
  3. Simplify and Solve for x: Simplify the equation by distributing the 2-2 into the parentheses.\newline2x+14x+4=40-2x + 14x + 4 = 40\newlineCombine like terms.\newline12x+4=4012x + 4 = 40
  4. Isolate x Term: Subtract 44 from both sides of the equation to isolate the term with xx.\newline12x+44=40412x + 4 - 4 = 40 - 4\newline12x=3612x = 36
  5. Solve for x: Divide both sides by 1212 to solve for x.\newline12x12=3612\frac{12x}{12} = \frac{36}{12}\newlinex=3x = 3
  6. Substitute xx into Equation 11: Now that we have the value of xx, we can substitute it back into Equation 11 to find the value of yy.\newliney=7(3)2y = -7(3) - 2\newlineCalculate the value of yy.\newliney=212y = -21 - 2\newliney=23y = -23
  7. Calculate yy: We have found the values of xx and yy that satisfy both equations in the system.\newlinex=3x = 3 and y=23y = -23\newlineThese values are the solution to the system of equations.

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