 When you're working with MyOpenMath, or for that matter, dealing with the real world, the thing to remember is that you are ultimately responsible for everything that you write. And if you mis-type something, the results can vary from difficult to troubling to catastrophic. And the thing to remember is that no computer ever got fired for typing the wrong thing. To type in rational expressions, we'll enter numerator slash denominator. Now MyOpenMath interprets your expression as you type it. So if you look here, we'll see what we've actually entered. And the important thing here is that if this isn't what we wanted to enter, we need to fix it. With fractions and rational expressions, the most likely problem is that we need to make sure that we group the denominator by using a set of parentheses. So let's throw the denominator into a set of parentheses. But before you click on submit, notice that MyOpenMath has said, I don't understand what you're saying. That's what it means by syntax error. And again, you're ultimately responsible for anything that you write. So if you make a mistake, it's on you. And again, no computer ever got fired for making a typo. Generally speaking, MyOpenMath will try to diagnose the problem. And here, it thinks there's a set of unmatched parentheses. And if we look at what we typed closely, we see that we accidentally doubled the parentheses. So let's fix that. And wait for it. MyOpenMath does syntax checking as you go, and so now it looks at what you've entered. That syntax error is gone, and so now it understands what you've written. It might not be the right answer, but at least MyOpenMath understands what you're saying. The use of parentheses does get more complicated as our expressions get more complicated. And again, MyOpenMath will display what you've actually typed in as your answer. And if this isn't what we wanted to type in, we need to fix it. So we'll throw the denominator inside a set of parentheses. And that's still not what we wanted, so we have to throw the numerator into a set of parentheses as well. And now, if this is what we really want to answer, we can click on submit. Now for the more complicated expressions, you might get lost in a sea of parentheses. And so here's something that you could do. If you click in the answer box and a yellow right up arrow shows up, clicking on that will open up a math formatting window. And this will allow you to type in your answer in a what you see is what you get format. So we want to enter in a rational expression, so we'll click on the fraction button, and then type in our expression. Clicking on save enters it. And again, we see what we've entered in, and it objects to this. It doesn't like it. And again, MyOpenMath will generally try to identify what the problem is. And here, it doesn't like our variables because, oh yeah, the problem's in A, but we entered in this X. So let's go back and fix that. So we can click on the yellow up arrow to reopen the math editor. And now it understands, so we can click submit. For square roots, we can use S, Q, R, T, and then the radicand. Oh wait, we can't. It doesn't like that. And it does give us some advice. We need to enclose the radicand in parentheses. So let's fix that. Again, if we click inside the answer box and the yellow up arrow appears, that will open up a formatting window. Or we can solve quadratic equations, so we type in our answer. Again, MyOpenMath will show us what we've actually entered, and if it's not what we wanted to enter, we'll need to fix it. And we only got 0.5 out of 1. And well, this is a quadratic equation. There should actually be two solutions. And if we are about to enter in the second one, so let's type in that second one. Well, that's not what we wanted to type in. Let's fix it. And as long as we're sure these are what we wanted to enter in, we can click submit.