This problem will help you learn the rules of precedence, that is, the
order in which mathematical operations are performed. You can use
either parentheses ( ), square brackets [ ], or curly braces
{ } if you want to change the normal way operations
work.
So first let us review the normal way operations are performed.
The rules are simple. Exponentiation is always done before multiplication
and division, and multiplication and division are always done before addition
and subtraction. (Mathematically we say exponentiation takes precedence over
multiplication and division, etc.). For example what is 1+2*3?
and what is ?
Now sometime you want to force things to be done in a different way. This is
what parentheses are used for. The rule is: whatever is enclosed in
parentheses is done before anything else (and things in the innermost
parentheses are done first).
For example how do you enter
Hint: this is a good place to use [ ]'s and also to use the
"Preview" button.
Here are some more examples:
(1+3)9 =36, (2*3)**2 = 6**2 = 36, 3**(2*2) = 3**4 = 81, (2+3)**2 = 5**2 = 25, 3**(2+2) = 3**4 = 81
(Here we have used ** to denote exponentiation and you can also
use this instead of a "caret" if you want). Try entering some
of these and use the "Preview" button to see the result. The
"correct" result for this answer blank is 36, but by using the
"Preview" button, you can enter whatever you want and use
WebWork as a hand calculator.
There is one other thing to be careful of. Multiplication and
division have the same precedence and there are no universal rules as
to which should be done first. For example, what does 2/3*4 mean?
(Note that / is the "division symbol", which is usually
written as a line with two dots, but unfortunately, this "line
with two dots" symbol is not on computer keyboards. Don't think of
/ as the horizontal line in a fraction. Ask yourself what 1/2/2 should
mean.) WebWork and most other computers read things from left to
right. That is, 2/3*4 means (2/3)*4 or 8/3, rather than 2/12. Some
computers may do operations from right to left. If you want 2/(3*4) =
2/12, you have to use parentheses. The same thing happens with
addition and subtraction. 1-3+2 = 0 but 1-(3+2) = -4. This is one case
where using parentheses even if they are not needed might be a good
idea, e.g. write (2/3)*4 even though you could write 2/3*4. This is
also a case where previewing your answer can save you a lot a grief
since you will be able to see what you entered.
Enter 2/3*4 and use the Preview button to see what you get.
You can earn partial credit on this problem.