Questions & Answers about Почему ты не решишь эту задачу?
Why does решишь translate to the future 'will solve' if it has a present-tense ending?
This is the magic of perfective verbs! The verb решить (to solve completely) is perfective, meaning it focuses on a finished result. Perfective verbs cannot be happening right now in the present. When you put regular present-tense endings on a perfective verb, it automatically creates the simple future tense.
How exactly do we form решишь from the dictionary form решить?
It follows the standard second conjugation. You drop the -ить from the infinitive решить and add the ending for ты (informal 'you'), which is -ишь.
Why does the sentence use эту задачу instead of the dictionary forms эта задача?
The task is the direct object of the sentence—it is the thing being solved. This means it must be in the accusative case. For feminine words, the ending -а changes to -у, so задача becomes задачу. The matching word for 'this' must also change to match, going from эта to эту.
What is the exact feeling of Почему ты не решишь here?
While it literally means 'Why will you not solve', in Russian this phrasing is often used to ask about someone's intentions or to make a suggestion. It sounds a bit like 'Why don't you just solve this task?' or 'Why not get this task done?', focusing on the final result.