The sum of three consecutive odd numbers is -21, how do you find the smallest number?

1 Answer
Feb 11, 2016

Answer:

#-5#

Explanation:

First things first, we have to analyze the question for clues. The question is: the sum of three consecutive odd numbers is -21, how do you find the smallest number?

Let's take it apart. SUM means addition. So we'll be adding #3# numbers together.

CONSECUTIVE mans that the numbers come right after each other, like #3, 4, 5#.

ODD. Okay, that mans that the numbers have to be odd. So the list would go more like #3, 5, 7#.

The negative in #color(red)(-)21# says that the numbers will be negative, because you cannot add positive numbers to get a negative number, so it has to be caused by negative values.

I think we have all the information now, so let's put it together. I'm going to start by putting in the numbers in order, starting at #-1# and going on from there, skipping the even numbers. So we start out with #(-1)+(-3)+(-5)=#... #-9#. So that didn't work. Let's try with #(-3)+(-5)+(-7)#. This equals... #-15#. Let's try another one. #(-5)+(-7)+(-9)#. This equals... #color(red)(-21)#! We got it! Let's just double check that it meets all the requirements, just to make sure.

Is it #3# consecutive odd numbers that add up to #-21#? Yep, yep, yep, and yep. We're good to go!

So, which is the smallest number out of #-5, -7, -9#? Well, the smallest is the number closest to zero on a numberline, and out of all three, #-5# is the closest to #0#. Great job!