machine learning octave code gradient descent question

Question

I'm taking Coursera Machine learning course. so who take this courses will able to help this problem.

this is the octave code to find the delta for gradient descent.

     theta = theta - alpha / m * ((X * theta - y)'* X)';//this is the answerkey provided

First question) the way i know to solve the gradient descent theta(0) and theta(1) should have different approach to get value as follow

     theta(0) = theta(0) - alpha / m * ((X * theta(0) - y)')'; //my answer key
     theta(1) = theta(1) - alpha / m * ((X * theta(1) - y)')'; //my answer key

but i'm not sure why the answer key only show

            theta = theta - alpha / m * ((X * theta - y)'* X)';

this equation.

Second question) what is the ' ' doing in octave code?

            theta = theta - alpha / m * ((X * theta - y)'* X)';
                                '* X)' // what ' ' thing do in here