The official solucionario is not sold publicly (it is reserved for teachers). However, Oxford Spain provides it for free in digital format to registered teachers and sometimes to students through their Bloom platform.
To give you an idea of the level of detail, here is a typical solved problem from Unit 9 – Derivatives: Solucionario Matematicas 1 Bachillerato Oxford Geniox Pro
Problem: Calculate the derivative of ( f(x) = \fracx^2e^x ). The official solucionario is not sold publicly (it
Solution from the Solucionario:
Each solution includes intermediate algebraic steps, not just the final answer. Each solution includes intermediate algebraic steps
This is the single most effective way to use the Geniox Pro Solucionario: