Question Summary:
Do we have to say the takbir along with the imam when he goes into ruku?

Question Detail:

 Do we have to say the takbir along with the imam when he goes into ruku and when he goes in and out of sajda etc or is the imam's recitation enough

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
 
It is Sunnah to repeat the Takbeer of Ruku and Sajdah along with the Imam.[1]
 
And Allah Ta’āla Knows Best
Saleem Ibn Sajawal Khan
Bradford, UK
Student Darul Iftaa

Checked and Approved by,
Mufti Ebrahim Desai.