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 how many real solutions intersection where there be in the system of two equations

 how many real solutions intersection where there be in the system of two equations-example-1

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Answer:

  • Two real solutions

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Given is the system of equations.

Solve it by substitution, x = y + 5:

  • 8x² + 5y² = 40
  • 8(y + 5)² + 5y² = 40
  • 8(y² + 10y + 25) + 5y² = 40
  • 8y² + 80y + 200 + 5y² = 40
  • 13y² + 80y - 160 = 0

Find the discriminant of the quadratic equation, if it is positive there are two real solutions, if zero then one solution, if negative then no solution.

  • D = 80² - 4*13*(-160)
  • D = 14720

Since D > 0 there are two real solutions (intersections).

User Arnaud Quillaud
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