Hi,
The other replies included instructions for superscripting the exponent.
There are, however, a few more things to consider.
1. Instead of the letter x, you can insert a real multiplication sign (×)
from the Symbol dialog box, by typing d7 and then pressing Alt+x, or by
creating an Autotext entry, an AutoCorrect sequence, or a shortcut key for it.
2. You might want to insert nonbreadking spaces before and after the
multiplication sign to prevent the expression from being broken by a line
break. This is easily done by pressing Shift+Cntrl+Spacebar instead of
pressing just the spacebar.
3. For the minus sign in the exponent, you can insert a real minus sign (−)
or an en dash (–) instead of an ordinary hyphen. The minus sign and en dash
are practically identical in appearance. The advantage of using the en dash
is that there is already a built-in shortcut key for it, Ctrl+-(num). The
advantage of the real minus sign is that it prevents line breaking in the
middle of the exponent. You can insert a real minus sign from the Symbol
dialog box, by typing 2212 and then pressing Alt+x, or by creating an
Autotext entry, an AutoCorrect sequence, or a shortcut key for it.
4. I personally find it faster and easier to create superscripts by pressing
Shift+Cntrl+=, typing the superscripted characters, and then pressing
Cntrl+Spacebar to return to ordinary formatting, rather than by going back
and selecting the characters to format after they are already typed. This
technique requires less keystrokes does not involve reaching for the mouse.