Question

What is twice a number, minus 13?

Answer 1

Hint: The easiest way to write algebraic expressions from a sentence is to look for the unknown quantity, and assume it to be a variable (say \[x\]). And then, we must perform suitable operations, as needed. We must keep in mind that the term ‘minus’ is the same as subtraction.

Complete step-by-step answer:
The verbal representation of required algebraic expression is “twice a number, minus 13.” Here, we do not have any information regarding the “number” mentioned in our above statement.
So, we are assuming this “number” to be \[x\].
Now, we will proceed by observing what operations are performed on this “number”.
The first part of our statement says “twice a number”.
We know that the word ‘twice’ denotes a multiplication by the number 2, that is, the number $x$ is multiplied by 2.
And so, our expression now becomes \[\left( 2x \right)\].
Now, let us move on to the next part of the statement. We now have the statement, “twice a number, minus 13”.
So, now by using our past steps, we can also write this statement as “\[\left( 2x \right)\] minus 13”.
So, our required expression now evaluates to \[\left( 2x-13 \right)\].
Hence, our required algebraic expression is \[\left( 2x-13 \right)\].

Note: We must carefully read that on which part of our expression, any specified operation is taking place. Some of us might express this as \[2\left( x-13 \right)\] which has a totally different meaning, and will be an incorrect answer.