How to Solve the System of Equations by Substitution: y = x² – 3x + 7 and 3x + y = 2

To solve the system of equations using substitution, we start with the equations:

  • Equation 1: y = x² – 3x + 7
  • Equation 2: 3x + y = 2

Since Equation 1 is already solved for y, we can substitute the expression for y in Equation 2.

Substituting y from Equation 1 into Equation 2 gives us:

3x + (x² – 3x + 7) = 2

Now, simplify the equation:

  • Combine like terms: x² – 3x + 7 + 3x = 2
  • This reduces to: x² + 7 = 2

Next, we need to rearrange this equation:

x² + 7 – 2 = 0

x² + 5 = 0

This means:

  • x² = -5

Since x² cannot equal a negative number in the set of real numbers, we conclude that there are no real solutions for x. However, if we consider imaginary numbers, we get:

  • x = ±√(-5) = ±i√5

Now, we can find the corresponding values for y by substituting these x values back into Equation 1:

y = (±i√5)² – 3(±i√5) + 7

y = -5 – 3(±i√5) + 7

This simplifies to:

y = 2 – 3(±i√5)

Therefore, the solutions for the system of equations are:

  • x = i√5, y = 2 – 3i√5
  • x = -i√5, y = 2 + 3i√5

In conclusion, the system does not have real solutions, but it does have complex solutions.

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