I just read an article on MSN about a tricky mathematical problem that apparently most people get wrong. The premise of the article is that, while (-9)^(2) \+ 81 would solve as 162, the lack of braces causes us to do the exponentiation first (PEMDAS) resulting in -81 + 81 = 0, which seems very incorrect as -9 isn’t an operation, it’s a literal. (PEMDAS doesn’t talk about a number’s sign.)
Stating a term of -9 doesn’t mean “take 9 and negate it”, it means “take the literal which is 9 less than 0”. Unless there’s some historical shorthand I’m missing here or something? Does -9 represent a shorthand for 0 – 9? Most programming languages treat a negative literal as a literal and not an operand. (In languages where you can override the – operand, specifying a number with a – in front of it still takes the literal without calling the operand override function.)
So, I guess my question is this: Does -9^(2) evaluate as (-9)^(2) = 81 or as -(9^(2)) = -81, and why?
Here’s the article in question.
[https://www.msn.com/en-us/lifestyle/parenting/tricky-equation-confuses-public-mathematical-misconception-leads-to-widespread-error/ar-BB1hD1mJ?rc=1&ocid=winp1taskbar&cvid=4a3ad03d63b84eb1d76097a4d6c147d3&ei=22](https://www.msn.com/en-us/lifestyle/parenting/tricky-equation-confuses-public-mathematical-misconception-leads-to-widespread-error/ar-BB1hD1mJ?rc=1&ocid=winp1taskbar&cvid=4a3ad03d63b84eb1d76097a4d6c147d3&ei=22)
Who’s right (me or the article) and why?
In: Mathematics
The trick is that we don’t typically write expressions that inefficiently. The expression would almost always be written as
81 – 9^2
and when you see that expression you don’t think twice about the answer being 0. Someone has rearranged the terms with, I presume, intentional misdirection.
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