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About John Zalewski
Expertise
I can help you solve problems involving fractions, decimals, ratios, and algebra. I can teach you how to do math faster, and even in your head. I can teach math definitions, and help you study, if necessary. Please do not ask any graphing, trigonometry, or calculus questions. Try to work through homework questions before asking for assistance.

Experience
I routinely process numbers of all kinds in my head, without need of a calculator.

Education/Credentials
I was an A math student while in high school.

You are here: Experts > Science > Math for Kids > Basic Math > Functions

Basic Math - Functions

Expert: John Zalewski - 6/16/2008

Question
Im studing to take a compass placement test and i totally forget how to solve this...

if f(4)=0 and f(6)=6, which of the following could represent f(x)?
a.2/3x-4
b.x+2
c.x-4
d.3/2x+6
e.3x-12

The study packet includes the answers and the answer is E. however i have no idea where to start. Can you help my please?

Answer
Hello, Kimberlee.

For 3x-12 to be the correct answer, it means that when x = 4, 3x-12 will equal 0. Likewise, when x = 6, 3x-12 will equal 6.

We can show this to be correct.

3(4) - 12 = 0.

3(6) - 12 = 6.

Since 12 - 12 equals 0 and 18 - 12 = 6, we know that e is the correct answer.

All of the other answers will prove to be incorrect. For example, c is incorrect because although 4-4 does equal 0, 6-4 does not equal 6.

Hope this helps.

Regards,
John

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