Today’s ACT question of the day is secretly asking if you know the meaning of y = mx + b.  We have to figure out which graph looks like y = 3x +1. Yes, you could graph that on your calculator, but if your graph’s scale doesn’t match the scale of the graphs in the test booklet, you might not find the answer that way.

Since b is the y-intercept, we know we need a graph that crosses the y-axis at 1. With a slope of positive 3, we know that the graph is going up and to the right, and that it might look a little steep compared to y = x (a good reference to have in your head).

That looks pretty good!  Choice C works.

Bonus:

Why isn’t it this one?