,
the grey key located to the left of the 
key. To subtract two numbers, use the black
minus key located above the
addition key.
The TI-89 calculator distinguishes, using different keys, between the unary operation of negation and the binary operation of subtraction.
| To enter a negative number, use the negation key, ,
the grey key located to the left of the key. To subtract two numbers, use the black
minus key located above the
addition key. |
|
For example, to subtract -5 from 17, compute 17 - (-5). Press
To enter the function y1 = -x, use the negation key, not the minus sign.