When the **solutions **have** irrational coordinates.**

**When a system must be solved algebraically?**

When we solve a **system graphically**, we must find the point where the **lines intersect**, and that is the solution. So this works better when the solutions are whole numbers and easy to read.

That is not the case for** irrational numbers**, finding the exact solution when it is **irrational **is almost impossible using the **graphing method**, so in these cases, we need to solve it** algebraically.**

Concluding, the correct option is B.

If you want to learn more about **systems of equations,** you can read:

brainly.com/question/13729904