Today’s SAT question of the day is a math question about function notation (the way functions are written).  This question is rated medium difficulty…maybe it’s just my years of tutoring talking, but I thought it was more like mega-easy (I solved it in less than10 seconds).

A function is just a relationship between values, right?  When x changes, y consistently changes in a related way.  And functions are written in a special format:

f(x) = ……

which means that “f of x”, or the function relating to x, is whatever appears on the other side of that equal sign.

This question also asks us about slope, so let’s think of what we know about slope:

Slope is rise / run.

Slope is represented by “m” in the classic linear equation y = mx + b.

(If any of that is news to you, email me and we can set up a 90-minute algebra refresher session to catch you up)

The question tells us that f is a line with slope 2. That means we need 2 in the m position, or an equation in our answer choices that says f(x) = 2x [doesn’t matter what comes next]. Only choice B has a slope of 2.

We defined the term function above, but there are a few other math terms to know when dealing with problems like this one:

• an equation is something with an equals sign, like a math sentence
• a linear equation is an equation that describes a line, such as y = mx + b
• the simplest definition of a coefficient is the value next to a variable – for instance, in the linear equation above, m is the coefficient of x