what is the evaluation?

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

what is the evaluation?

Tutors, please sign in to answer this question.

Scottsdale, AZ

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

Saugus, MA

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

Chicago, IL

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. :-)

Wesley L.

Premier MIT Math Tutor and SHSAT/SAT/ACT Specialist

New York, NY

5.0
(229 ratings)

Robert E.

Experienced Physics and Math Tutor

Jamaica, NY

4.9
(505 ratings)

Cassandra K.

Creative and Engaging Math and English Tutor

New York, NY

5.0
(302 ratings)

- Algebra 2 3295
- Algebra 4917
- Math 9377
- Prealgebra 167
- Algebra Help 952
- Geometry 1813
- Algebra Word Problem 2413
- Math Help 5199
- Word Problem 4946
- Precalculus 1481