إِنَّ الْمُعَلِّمَاتِ مُجْتَهِدَاتٌ
Translation: Indeed, the female teachers are diligent.
«الْمُعَلِّمَاتِ»: accusative ism inna with kasra, as a sound feminine plural.
«مُجْتَهِدَاتٌ»: nominative khabar inna with ḍamma.
An accusative grammatical role does not always imply a visible fatḥa.