Math Problem Statement

Solve the simultaneous equations: x^2 + y^2 = 41 and y = 2x - 3.

Solution

We are given two simultaneous equations to solve:

x^2 + y^2 = 41 \tag{1} y = 2x - 3 \tag{2}

Step 1: Substitute Equation (2) into Equation (1)

From Equation (2), we know that y=2x3y = 2x - 3. We substitute this expression for yy into Equation (1):

x2+(2x3)2=41x^2 + (2x - 3)^2 = 41

Step 2: Expand and Simplify

Expand (2x3)2(2x - 3)^2:

(2x3)2=(2x)22(2x)(3)+(3)2=4x212x+9(2x - 3)^2 = (2x)^2 - 2(2x)(3) + (-3)^2 = 4x^2 - 12x + 9

Substitute this back into the equation:

x2+4x212x+9=41x^2 + 4x^2 - 12x + 9 = 41

Simplify:

5x212x+9=415x^2 - 12x + 9 = 41

Step 3: Solve the Quadratic Equation

Move all terms to one side:

5x212x+941=05x^2 - 12x + 9 - 41 = 0

5x212x32=05x^2 - 12x - 32 = 0

Now solve this quadratic equation using the quadratic formula:

x=(12)±(12)24(5)(32)2(5)x = \frac{-(-12) \pm \sqrt{(-12)^2 - 4(5)(-32)}}{2(5)}

x=12±144+64010x = \frac{12 \pm \sqrt{144 + 640}}{10}

x=12±78410x = \frac{12 \pm \sqrt{784}}{10}

x=12±2810x = \frac{12 \pm 28}{10}

Thus, we have two solutions for xx:

x=12+2810=4010=4x = \frac{12 + 28}{10} = \frac{40}{10} = 4

x=122810=1610=1.6x = \frac{12 - 28}{10} = \frac{-16}{10} = -1.6

Step 4: Find Corresponding yy Values

For x=4x = 4:

y=2(4)3=83=5y = 2(4) - 3 = 8 - 3 = 5

For x=1.6x = -1.6:

y=2(1.6)3=3.23=6.2y = 2(-1.6) - 3 = -3.2 - 3 = -6.2

Final Solutions

The solutions to the system are:

(x,y)=(4,5)or(x,y)=(1.6,6.2)(x, y) = (4, 5) \quad \text{or} \quad (x, y) = (-1.6, -6.2)

Would you like more details on any of these steps, or do you have further questions?

Here are 5 related questions:

  1. What other methods could be used to solve simultaneous equations, such as graphing?
  2. How does the discriminant of a quadratic equation help in predicting the nature of the solutions?
  3. Can simultaneous equations have more than two solutions? If so, under what circumstances?
  4. What are some real-world applications of solving simultaneous equations like these?
  5. How can you check whether a solution is correct when solving simultaneous equations?

Tip: Always substitute your solutions back into both original equations to verify that they satisfy both conditions.

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Math Problem Analysis

Mathematical Concepts

Simultaneous Equations
Algebra
Quadratic Equations

Formulas

Quadratic equation formula: ax^2 + bx + c = 0
Equation of a circle: x^2 + y^2 = r^2
Substitution method for simultaneous equations

Theorems

Quadratic Formula: x = (-b ± √(b² - 4ac)) / 2a

Suitable Grade Level

Grades 9-12