Find the common difference of the arithmetic sequence - 11, - 20, - 29, ...

-9

Step-by-step explanation:

Firstly, let's define the common difference of an arithmetic sequence:

it's the real number that we add to a term of the sequence to get the next term.

→ (-20) - (-11) = -9, here we added (-9) to (-11) to get (-20)

→ (-29) - (-20) = -9, here we added (-9) to (-20) to get (-29)

conclusion: the common differenc is - 9