Preview: Find Missing Numbers Using Inverse Operations in an Algebraic Expression
Need Help?
Introduction
In this activity, we will learn how to express an odd number as 'double a number plus one' and then identify whether the result is an odd or even number.
Example
Write this odd number as 'double a number plus one'. Then say whether the answer is odd or even.
209 = 2 x ______ + 1
Answer
To solve this, we need to start with the answer of 209 and do the opposite (inverse) to it.
The inverse of adding 1 is subtracting 1.
The inverse of multiplying by 2 (doubling) is to divide by 2 (halving)
So, we do 209 - 1 = 208
208 ÷ 2 = 104
209 = 2 x 104 + 1, which is the same as 'double 104 plus one'.
The number 104 is an even number, since it is divisible by 2.
In this activity, we will learn how to express an odd number as 'double a number plus one' and then identify whether the result is an odd or even number.
Example
Write this odd number as 'double a number plus one'. Then say whether the answer is odd or even.
209 = 2 x ______ + 1
Answer
To solve this, we need to start with the answer of 209 and do the opposite (inverse) to it.
The inverse of adding 1 is subtracting 1.
The inverse of multiplying by 2 (doubling) is to divide by 2 (halving)
So, we do 209 - 1 = 208
208 ÷ 2 = 104
209 = 2 x 104 + 1, which is the same as 'double 104 plus one'.
The number 104 is an even number, since it is divisible by 2.
Does that make sense?
Let's try some questions.
Question
/ 10
Preview only, get started for free to complete this activity
Your tutor needs to mark this activity before you continue
Teacher explanation