Hi GMATters,
As part of my ongoing project to democratize more of my content, I’ve published my entire 20-page Functions Guide/video course on the website. Previously available only to private clients.
You’re welcome to download it as a PDF from the site, but it’s all published there if you just want a nice, long scroll.
Hope you enjoy!
Rowan
https://yourgmatcoach.com/how-to-beat-gmat-functions-problems-once-and-for-all--------------------------------
There are few words that strike terror into testtakers more than “functions.”Wait for it…
Yeah, that feeling. The dropping in the pit of the stomach, the hyperventilating. We’ve all been there.
Let’s not waste time trying to make functions sound simple or appealing; you don’t have to like them! You just need to learn a few actionable techniques to getting past them.
What is a Function?
Does it matter?
A little bit, but only to this degree: a function is just an equation. You know, you take a number and you feed it into the equation and then it poops something out the other end and you have an answer.
Well, “function” is just a clever word for the exact same thing, but just slightly rearranged!
Let’s say that I take the value of x^2 - 1 when x = 3.
Pretty easy, right? You’d just replace the x with the 3 and that would give you this:
3^2 - 1 = 9 - 1 = 8
So that’s pretty straightforward, right? If it’s not, shoot me an e-mail and I’ll see if I can help out.
Now let’s phrase it like this:
If the function f(x) = x^2 - 1, then what is the value of f(3)?
Let’s solve this tremendously complicated progresion of our idea:
Move up six lines and do the exact same thing you did before: replace the x with a 3.
Yup, kids, that’s a function. That’s all. When you get an f (3) or f (5) or f (37) you simply replace the x with whatever is now within the brackets, then continue the calculation.
ASIDE:Practice SAFE X (sorry!): when replacing the x, always surround the new number with brackets.
Back to the lecture…
That is, if we have:
f(x) = x^2 - 1
And the testwriters ask what f(3) is, it is written like this:
(3)^2 - 1 = 9 - 1 = 8
So in the end it’s up to you, but don’t come crying to me when you tripped over a negative sign and fell on your face.
As a note, you might be wondering why this doesn’t have technical f(x) notation. It’s still a substitution question–in a few pages, we will address how any substitution question can be written as a function!
Another Way to Look at GMAT Functions ProblemsYou know that program that Microsoft created for no other reason than to confuse the living **** out of people called “Excel?”
Or perhaps you use Excel every day and it’s only my practical-ass mind simply can’t wrap my head around its silliness. Hey, if you like the Excel, this will be great for you.
Look at it this way: a function is basically just an Excel macro written on the page.
To go back to our original example, if you’re given f(3), that’s the same as simply putting a 3 in a column associated with the macro:
x^2 - 1
That’s obviously going to give this:
(3)^2 - 1 = 9 - 1 = 8
Done. Dusted.
Attack of the Over-Complicated GMAT Functions ProblemsYou know how function explanations always talk about “Domain” and “Range?”
(Yes, even if you learned it for SAT. This is one place where the GMAT is easier than the SAT. Forget that stuff: it is useless.)
You really don’t need to know the terminology, so my prescription is to ignore it with prejudice.
Sometimes, however, it’s useful to have a tool to rely upon…
In more complicated functions questions, I suggest drawing a table. All you need to do is to think about the INPUT and the OUTPUT…
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You can find the rest here:
https://yourgmatcoach.com/how-to-beat-gmat-functions-problems-once-and-for-all