Question

Noah says that is equivalent to , because the subtraction sign tells us to subtract everything that comes after .
Elena says that is equivalent to , because the subtraction only applies to .
Do you agree with either of them? Explain your reasoning.

Answer 1

Answer:  Elena is correct, because when you add the coefficients using the Associative property of addition  you get $11x$.

Step-by-step explanation:

The complete exercise is: Noah says that $9x - 2x + 4x$ is equivalent to $3x$, because the subtraction sign tells us to subtract everything that comes from after $9x$. Elena says that $9x - 2x + 4x$ is equivalent to $11x$, because the subtraction only applies to $11x$. Do you agree with either of them?

You have the following expression given in the exercise, where you have a variable "x":

 $9x - 2x + 4x$

Since each term has the same variable, they are like terms you can add them all.

By definition, you need to add the coefficients of the variables (You need to remember that the coefficients are the numbers next to the variable).

You can use the Associative property of addition to solve the exercise. This states that:

$(a+b)+c=a+(b+c)$

Then, you can group the first two terms of the expression, add them and then add the sum obtained to the other term.

Therefore, you get the following result:

$9x - 2x + 4x=(9x - 2x) + 4x=7x+4x=11x$

So, you can conclude that Elena is correct.