Question 990597

I have a question for example

1/2xy^2 when x is 4 and y is -2 do you have to put the expression like

1/2*4*-2^2
Or
1/2*4*(-2)^2 with the parentheses? I always gets confuse
<pre>{{{(1/2) * 4(- 2)^2}}} is correct since you have to SQUARE the value of y, which is - 2. 

First expression: {{{(1/2) * 4 * - 4}}} ------> {{{2 * - 4}}} ------> {{{- 8}}}.
Second expression: {{{(1/2) * 4 * 4}}} -------> {{{2 * 4}}} --------> {{{8}}}.
Do you see the difference?