Math Problem Statement

how many ordered pair (x,y), satisfy the system equations 3x+2y=1 and y=x^2-4x-5?

Solution

To determine the number of ordered pairs (x,y)(x, y) that satisfy the given system of equations:

  1. 3x+2y=13x + 2y = 1
  2. y=x24x5y = x^2 - 4x - 5

we can substitute the expression for yy from the second equation into the first equation and solve for xx.

Step-by-Step Solution:

1. Substitute yy from the second equation into the first equation:

3x+2(x24x5)=13x + 2(x^2 - 4x - 5) = 1

2. Expand and simplify the equation:

3x+2x28x10=13x + 2x^2 - 8x - 10 = 1

Combine like terms:

2x25x11=02x^2 - 5x - 11 = 0

3. Solve the quadratic equation for xx:

To solve for xx, we use the quadratic formula:

x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

where a=2a = 2, b=5b = -5, and c=11c = -11.

Calculate the discriminant Δ=b24ac\Delta = b^2 - 4ac:

Δ=(5)242(11)\Delta = (-5)^2 - 4 \cdot 2 \cdot (-11)

Δ=25+88\Delta = 25 + 88

Δ=113\Delta = 113

Since the discriminant is positive (113>0113 > 0), there are two distinct real solutions for xx.

4. Find the values of xx:

x=(5)±11322x = \frac{-(-5) \pm \sqrt{113}}{2 \cdot 2}

x=5±1134x = \frac{5 \pm \sqrt{113}}{4}

So, the two solutions for xx are:

x1=5+1134,x2=51134x_1 = \frac{5 + \sqrt{113}}{4}, \quad x_2 = \frac{5 - \sqrt{113}}{4}

5. Find corresponding yy values for each xx:

Substitute x1x_1 and x2x_2 back into the equation for yy:

y=x24x5y = x^2 - 4x - 5

Calculate y1y_1 for x1x_1:

y1=(5+1134)24(5+1134)5y_1 = \left( \frac{5 + \sqrt{113}}{4} \right)^2 - 4 \left( \frac{5 + \sqrt{113}}{4} \right) - 5

Calculate y2y_2 for x2x_2:

y2=(51134)24(51134)5y_2 = \left( \frac{5 - \sqrt{113}}{4} \right)^2 - 4 \left( \frac{5 - \sqrt{113}}{4} \right) - 5

6. Conclusion:

There are two distinct ordered pairs (x,y)(x, y) that satisfy the system of equations.


Would you like more details or have any other questions? Here are some related questions:

  1. How do you find the exact values of y1y_1 and y2y_2 in this context?
  2. What is the geometric interpretation of the solution for this system of equations?
  3. Can you graph both equations to visualize their intersection points?
  4. What if the discriminant were zero or negative—how would that change the number of solutions?
  5. How can this method be applied to solve other types of nonlinear systems?

Tip: Solving systems of equations by substitution is particularly useful when one equation is linear and the other is nonlinear.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Systems of Equations
Quadratic Equations

Formulas

Quadratic formula

Theorems

-

Suitable Grade Level

Grades 10-12