39 times 31 is 1209, but what is the answer if both 39 and 31 are negative numbers? Here we will determine if the answer to negative 39 times negative 31 is positive 1209 or negative 1209.
There are many different ways to explain and determine if the answer to negative 39 times negative 31 is -1209 or +1209 using mathematical terms such as additive inverse and mathematical laws like the Distribute Law.
We will take a different approach - process of elimination: We will simply test if -1209 is the correct answer using basic algebra.
We will test if -1209 is correct by setting up the equation negative 39 times negative 31 equals negative 1209, and then simplifying the equation to see if it is true.
(-39) (-31) = (-1209)
Divide both sides of the equation by (-31) :
|
| = |
|
The numerator and denominator on the left side both have (-31) which even each other out and can be removed:
| (-39) = |
|
The numerator and denominator on the right side both have a minus sign (-) which even each other out and can be removed:
| (-39) = |
|
A numerator of 1209 and denominator of 31 on the right side is the same as 1209 divided by 31 which is 39. Now we end up with this untrue equation:
(-39) = (39)
-39 is NOT equal to 39, thus we have proven that negative 39 times negative 31 is not equal to -1209. The answer must therefore be 1209:
-39 x -31 = 1209
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 39 times negative 31 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 39 times negative 32?
Here is the next problem on our list that we have explained and calculated.
Copyright | Privacy Policy | Disclaimer | Contact