This is the 2713th most frequent Arabic word.
بذلك
"بذلك" means "with that" or "by that" in English.
Here, "بذلك" connects the result (success) to the means (great effort).
نجحت في الامتحان بذلك الجهد الكبير.
I succeeded in the exam with that great effort.
In this sentence, "بذلك" relates the possibility of achieving a goal to the attribute (persistence).
يمكنك الوصول إلى هدفك بذلك المثابرة التي لديك.
You can achieve your goal with that persistence you have.
"بذلك" is used to specify the reason or factor for the teacher's impression (the smart solution).