Intersecting Graphs (DP IB Applications & Interpretation (AI): HL): Revision Note

Intersecting graphs

How do I find the points of intersection between two graphs?

• Plot both graphs on your GDC

  • then use the intersect function to find the coordinates of the points of intersection

• The coordinates of the points of intersection

  • are solutions to simultaneous equations

How can I use graphs to solve equations?

• To solve $f\left(x\right)=a$

  • Plot the two graphs $y=f\left(x\right)$ and $y=a$ on your GDC

  • Find the points of intersection

    • The $x$-coordinates are the solutions of $f\left(x\right)=a$

• To solve $f\left(x\right)=g\left(x\right)$

  • Plot the two graphs $y=f\left(x\right)$ and $y=g\left(x\right)$ on your GDC

  • Find the points of intersections

  • The $x$-coordinates are the solutions of $f\left(x\right)=g\left(x\right)$