Which of the following functions are linear? Select all that apply. The function that assigns to each number z the value 9x?. The function that assigns to each positive number r the value . O The...

Extracted text: Which of the following functions are linear? Select all that apply. The function that assigns to each number z the value 9x?. The function that assigns to each positive number r the value . O The function that assigns to each positive number z the value 5/2x. The function that assigns to each number z the value 7x. O The function that assigns to each number z the value x. The function that assigns to each number z the value r + 8.