How do you insert parentheses to make #3^2-9*2+1=8# true?

1 Answer
Jan 11, 2018

Answer:

#9 - (9 xx 2) + 1 = -8#

Explanation:

Parentheses are the ultimate defining mark for algebraic order of operations. Their proper use removes all ambiguity in the order in which a series of operations should take place. So, the solution is just to define the correct order of combination to arrive at the desired value of 8 at the end.
#3^2# is already a value, so just convert it: #9#.

#9 - 9 xx 2 + 1 = 8# We can't combine the first two terms, because they become 0. 2 + 1 x 9 is way beyond the desired final value. So combine the middle ones first.
#9 - (9 xx 2) + 1 = 8# ; #9 - 18 + 1 = 8# Now it doesn't matter what the order is, although we end up with a -8 instead of +8, which looks like an error in the problem statement.
So, a final "parenthetical" order could be:
#9 - (9 xx 2) + 1 = -8#