Questions & Answers about Meine neue Spülmaschine ist sehr leise.
Why does neue end in -e here?
Because it comes right before a feminine noun (Spülmaschine) and follows the possessive article meine. In the nominative (subject) case, an adjective after meine, eine, or keine for a feminine noun always takes an -e ending.
Why doesn't leise have an ending like neue does?
leise comes after the verb ist rather than directly in front of a noun. In German, adjectives only get endings when they are placed right before the noun they describe. When they simply describe the subject after a verb, they stay in their basic dictionary form.
How do I know that Spülmaschine is feminine?
It is a compound noun ending in Maschine. Compound words always take the gender of their final word. Since it is die Maschine (following the helpful rule that most German nouns ending in -e are feminine), the whole word is feminine.
Could I use Waschmaschine instead of Spülmaschine?
No, they are used for different chores! A Spülmaschine comes from spülen (to rinse) and specifically means a dishwasher. A Waschmaschine is a washing machine for clothes.