<p>I was doing some math practice in the blue book, and don't understand the explanations for one of the problem I got wrong. It is #17 in section 2 of the 6th test (page 704). I would post it, but it is a graph problem. The books says the answer is C, which is a shift to the left, but i though adding 2 to X would cause a shift to the right. Can anyone clear this up for me?</p>
<p>nope… just remember that if its something like (x-2)^2 then it moves to the right but in your case it is +2, therefore you move to the left.</p>
<p>Let’s take a sample function:
y = x^2</p>
<p>Now let’s alter it:</p>
<p>y = (x - a)^2
This function has moved a to the right</p>
<p>Let’s make another alteration:</p>
<p>y = (x + a)^2
This function has moved a to the left.</p>
<p>It’s non-intuitive, but it makes sense if you think about it. For the original function, an x value of a would give us a y value of 0. For y = (x - a)^2, we need an x value of +a to get 0, so we moved +a on the x axis to get a y value of 0, in contrast to get the same y value for x = 0 in y= x^2. In y = (x + a)^2 we need an x value of -a to get 0, so we’re moving -a units on the x-axis to get a y value of 0, whereas in y = x^2 we use x = 0 to get y = 0. Similarly, every point of the graph is shifted -a units for y = (x + a)^2 or +a units for y = (x - a)^2</p>
<p>I meant that for the original function, y = x^2, an x value of 0 would get you a y value of 0. Sorry if that confused you.</p>
<p>Oh that makes sense now. Thank you for the explanation.</p>