What is negative 2 times negative 39? (-2 x -39)

What is negative 2 times negative 39?

2 times 39 is 78, but what is the answer if both 2 and 39 are negative numbers? Here we will determine if the answer to negative 2 times negative 39 is positive 78 or negative 78.

There are many different ways to explain and determine if the answer to negative 2 times negative 39 is -78 or +78 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 -78 is the correct answer using basic algebra.

We will test if -78 is correct by setting up the equation negative 2 times negative 39 equals negative 78, and then simplifying the equation to see if it is true.

(-2) (-39) = (-78)

Divide both sides of the equation by (-39) :

		(-2) (-39)
		(-39)

		(-78)
		(-39)

The numerator and denominator on the left side both have (-39) which even each other out and can be removed:

(-2) =

		(-78)
		(-39)

The numerator and denominator on the right side both have a minus sign (-) which even each other out and can be removed:

(-2) =

		(78)
		(39)

A numerator of 78 and denominator of 39 on the right side is the same as 78 divided by 39 which is 2. Now we end up with this untrue equation:

(-2) = (2)

-2 is NOT equal to 2, thus we have proven that negative 2 times negative 39 is not equal to -78. The answer must therefore be 78:

-2 x -39 = 78

The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 2 times negative 39 will always have a positive answer.

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