what is the evaluation?

Tutors, sign in to answer this question.

Let u = 2x+1. Then 2x-5 = 2x+1-6 = u-6, and 2x-2 = 2x+1-3 = u-3.

So,

2x-5=3(2x-2)-15 becomes,

u-6 = 3(u-3)-15=> u-6 = 3u-24

=> 18 = 2u

=> u = 9

Answer: 2x+1 = 9

2x-5=3(2x-2)-15

2x-5=6x-6-15

2x-5=6x-21

21-5=6x-2x

16=4x

x=4

2x+1=2(4)+1=8+1=9

Simon S. | Purveyor of Analytical ToysPurveyor of Analytical Toys

One thing which might be confusing in this problem is the wording. "What is the evaluation of 2x+1" is just funky math-speak for "what number is 2x+1 once you plug in x." To do this, we can solve the equation they give us, and then we'll plug in x.

Let me show you a similar example: Given that 3x - 2 = 4(2x - 2) - 14, what is the evaluation of 3x + 2?

We'll start by solving for x:

3x - 2 = 4(2x - 2) - 14

3x - 2 = 8x - 8 - 14

3x - 2 = 8x - 22

+22 +22

3x + 20 = 8x

-3x -3x

20 = 5x

/5 /5

4 = x

Now we know that x is 4. Therefore, 3x+2 *evaluates *to 3(4) + 2, which is better known to its friends as 14.

Take home message: The phrase "evaluation" means "what number do you get when you plug in for all of the variables." Hopefully this is enough to help you make some progress. :-)

Already have an account? Log in

By signing up, I agree to Wyzant’s terms of use and privacy policy.

Or

To present the tutors that are the best fit for you, we’ll need your ZIP code.

Your Facebook email address is associated with a Wyzant tutor account. Please use a different email address to create a new student account.

Good news! It looks like you already have an account registered with the email address **you provided**.

It looks like this is your first time here. Welcome!

To present the tutors that are the best fit for you, we’ll need your ZIP code.

Please try again, our system had a problem processing your request.