Editing an Expression

Editing an expression involves two steps:

  1. Putting the right part of the expression between the math editing lines.

  2. Pressing the correct key.

The meaning of each keystroke depends on what's between the editing lines.

This tutorial shows you a few tricks to editing math quickly without having to retype everything. However, the best way to learn how to create and edit expressions is to practice entering your own expressions.

Tutorial - Editing Math Expressions

Examples

sample expression

Review the information below to see what happens to the expression above when you press a particular key.

Delete

sample expression

Pressing [Delete] deletes whatever is immediately to the right of the insertion line. In this case, it deletes the exponent operator.

Backspace

 sample expression

Pressing [Backspace] deletes whatever is immediately to the left of the insertion line, in this case, the variable "b." The black rectangle is a placeholder to show you where to type something to make exponentiation work correctly.

sample expression

However, when the expression to be deleted is something more complicated than a name or a number, pressing [Backspace] or [Delete] first highlights it as shown. It can only be deleted by pressing the key a second time, making it harder to accidentally delete an expression.

Spacebar

sample expression sample expression sample expression

Pressing [Spacebar] lengthens the editing lines so that more of the expression fits between them. Pressing [Spacebar] again makes the editing lines now enclose the next larger expression.

Right and Left Arrows

When you press the right arrow, the insertion line moves to whatever is to the right, likewise the left arrow moves the insertion line to the left.

sample expression sample expression

Up and Down Arrows

sample expression sample expression

Since the insertion point is up in the exponent, the down arrow moves the editing lines from the exponent down to the "b."

Plus Key

sample expression sample expression

The general rule is that whatever is between the editing lines becomes the first operator you type.

In this example, the operator you typed is "+." The editing lines held the "b." That's why the "b" became the first operand of the "+." Note the placeholder waiting for you to supply the second operand of the plus.

Backslash Key

sample expression sample expression

In this example, the operator is "square root" and the editing lines held the "b." That's why the "b" went inside the square root.

sample expression sample expression

In this example, the editing lines held the entire denominator. As a result, the entire denominator becomes an operand of the square root as shown.

Insert Key

sample expression sample expression

Pressing the [Insert] key toggles the insertion line from one side to the other.

sample expression sample expression

Since the vertical arm was on the right, pressing [Insert] makes it jump to the left. This is useful, for example, when deleting a negation sign, which appears in front of an expression, rather than between two expressions.

-(a + b)

Press [Backspace] to delete the negation sign. Similarly, to delete a pair of parentheses, move the insertion point to the right of the "("

a + (b + c)

and press [Backspace]. You cannot delete one parenthesis at a time. Whenever you delete one, you automatically delete the other.

Inserting Parentheses

To insert a pair of parentheses:

  1. Enclose the expression between the editing lines.

    x squared

  2. Press the apostrophe (') to insert parentheses.

    (x squared)

You may also enter parentheses one at a time as you are entering expressions.

Related Topics