The problem
When simplifying how can I enter the value of a variable?
Second, in this particular expression, why is the first 2 converted to a negative?
Answer provided by our tutors
Introduce a variable into an equation rather than an expression and that will allow you to solve for the variable. For example, "3x+4x" can be simplified to '7x' but the equation "3x+4x=14" can be solved for 'x'.
If your problem contains no equals sign and you wish to simply an expression then please select one of the tabs for 'Simplify', 'Expand' or 'Factor'. If your problem contains an equals sign then please select the tab for 'Solve' or 'Graph'.
Finally, parentheses are important. The negative sign in front of '-6^2' is not "attached" to '6^2' and is simply treated as the first element of the expression "2*-6^2', yielding '-2*6^2'. Applying parentheses can yield to different answers, as shown in the following images:
