Use power series representations - visual power-series partial sums item
Case A4. For the geometric power series with ratio 0.4, enter its sum.
Worked practice: result and interpretation
Calculate the requested result first, then choose the interpretation that follows from it.
Write a full answer
Now write the response in full, in your own words — this is what the exam asks for. The AI marks it on the same moves you built above (focus, evidence, technique, judgement) and gives feedback on reasoning, evidence, and expression.