Texas Instruments TI-80 User Manual - Page 47

Implied Multiplication Parentheses Negation The TI-80 recognizes implied multiplication. For example, it understands 2p, 4SIN 45, 5(1+2), and (2×5)7 as implied multiplication. All calculations inside a pair of parentheses are completed first. For example, in the expression 4(1+2), EOS first evaluates the portion inside the parentheses, 1+2, and then multiplies the answer, 3, by 4. You can omit any right (closing) parenthesis at the end of an expression. All "open" parenthetical elements are closed automatically at the end of an expression and preceding the ! (store) or display-conversion instructions. Note: Parentheses are also used to enclose the arguments for certain functions, for example, NDERIV(Añ,A,6). In these cases, parentheses do not indicate implied multiplication. To enter a negative number, use the negation function. Press ·, and then enter the number. On the TI-80, negation is in the fourth group in the EOS hierarchy. Functions in the first group, such as squaring, are evaluated before negation. For example, LXñ is a negative number (or 0); L9ñ is L81. Use parentheses to square a negative number: (L9)ñ. Note: Use the | key for subtraction and the · key for negation. If you press | to enter a negative number, as in 9 p | 7, or if you press · to indicate subtraction, as in 9 · 7, it is an error. If you press ? A · ? B, it is interpreted as implied multiplication (A QLB). Operating the TI-80 1-21