Math Problem Statement

Find the coordinates of the general solution for the system of equations: x + y = 7 and x^2 + y^2 = 25.

Solution

You have provided two equations:

  1. x+y=7x + y = 7
  2. x2+y2=25x^2 + y^2 = 25

We need to find the coordinates (x,y)(x, y) that satisfy both equations. Let's solve this system of equations.

Steps:

  1. From the first equation, solve for yy: y=7xy = 7 - x

  2. Substitute y=7xy = 7 - x into the second equation: x2+(7x)2=25x^2 + (7 - x)^2 = 25

  3. Expand the equation: x2+(4914x+x2)=25x^2 + (49 - 14x + x^2) = 25 Simplify: 2x214x+49=252x^2 - 14x + 49 = 25

  4. Subtract 25 from both sides: 2x214x+24=02x^2 - 14x + 24 = 0 Simplify: x27x+12=0x^2 - 7x + 12 = 0

  5. Solve this quadratic equation using the quadratic formula: x=(7)±(7)24(1)(12)2(1)x = \frac{-(-7) \pm \sqrt{(-7)^2 - 4(1)(12)}}{2(1)} Simplify: x=7±49482=7±12x = \frac{7 \pm \sqrt{49 - 48}}{2} = \frac{7 \pm 1}{2} Thus, the solutions for xx are: x=7+12=4orx=712=3x = \frac{7 + 1}{2} = 4 \quad \text{or} \quad x = \frac{7 - 1}{2} = 3

  6. Substitute these values of xx back into the equation y=7xy = 7 - x to find the corresponding yy values:

    • If x=4x = 4, then y=74=3y = 7 - 4 = 3
    • If x=3x = 3, then y=73=4y = 7 - 3 = 4

Final Answer:

The two sets of coordinates that satisfy both equations are: (4,3)and(3,4)(4, 3) \quad \text{and} \quad (3, 4)

Would you like further details or have any questions?

Here are 5 related questions to expand on this topic:

  1. How can this system of equations be solved graphically?
  2. Can we generalize this method for any similar pair of equations?
  3. What is the geometric interpretation of the equations x+y=7x + y = 7 and x2+y2=25x^2 + y^2 = 25?
  4. How does the quadratic formula work, and what is its derivation?
  5. What are other methods for solving systems of non-linear equations?

Tip: Always check both possible solutions by substituting them back into the original equations to verify their correctness.

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations
Quadratic Equations

Formulas

Quadratic equation: ax^2 + bx + c = 0
Equation of a circle: x^2 + y^2 = r^2

Theorems

Quadratic formula
Substitution method

Suitable Grade Level

Grades 8-10