Applications of Integration: Background You’ll Need 2

  • Find out if and where two graphs cross each other

Determine Where Two Functions Intersect

Understanding where two functions intersect is a fundamental concept in algebra and calculus. This process can reveal key insights into the relationship between the functions and is crucial for graph analysis and solving system of equations.

To find where two functions intersect, the key is to understand that the intersection points are where the outputs of both functions are equal. This involves setting the equations of the functions equal to one another and solving for the variables involved. The solutions to these equations represent the coordinates of the points where the graphs of the functions intersect.

intersection of functions

The intersection of functions refers to the set of points where the graphs of two or more functions meet or cross each other. This occurs when the output values of the functions are equal at the same input value.

To determine where two functions intersect, set their equations equal to each other and solve for the variable. This process finds the exact points where the graphs of the functions meet.

Consider finding the intersection of the linear function [latex]f(x) = 2x+3[/latex] and the quadratic function [latex]g(x)=x^2+x+1[/latex].

We start by setting the equations equal to one another.

[latex]2x+3=x^2+x+1[/latex]

Next we rearrange the equation to isolate [latex]x[/latex] to one side and set the equation equal to zero.

[latex]0=x^2-x-2[/latex]

We can solve for [latex]x[/latex] by factoring.

[latex](x-2)(x+1)=0[/latex]

[latex]x = 2 \text{ and } x=-1[/latex]

For [latex]x=2[/latex], substituting back into [latex]f(x)[/latex] gives [latex]y=7[/latex]. For [latex]x=-1[/latex], [latex]y=1[/latex].

Thus, the interaction points are [latex](2,7)[/latex] and [latex](-1,1)[/latex].

How to: Find Intersection Points

  1. Set Equations Equal: Align the functions such that [latex]f(x)=g(x)[/latex]. This step equates the two functions’ outputs at their intersection points.
  2. Rearrange the Equation: Simplify the equation to isolate terms involving [latex]x[/latex] on one side. This often involves subtracting one side of the equation from the other.
  3. Solve for [latex]x[/latex]: Use algebraic methods such as factoring, applying the quadratic formula, or computational tools to find the value(s) of [latex]x[/latex] where the functions intersect.
  4. Find Corresponding [latex]y[/latex] Values: Substitute the [latex]x[/latex] values back into either original function to find the corresponding [latex]y[/latex] values for each intersection point.

Find the points of intersection of the functions [latex]y=x+2[/latex] and [latex]y=x^2+3x+2[/latex].

Find the points of intersection of the functions [latex]y=x-2[/latex] and [latex]y=2x^2-4x+1[/latex].