Question

On the graph of 𝑓(𝑥)=3sin(4𝜋𝑥), points 𝑃 and 𝑄 are at consecutive lowest and highest points with 𝑃 occurring before 𝑄. Find the slope of the line which passes through 𝑃 and 𝑄.
oobleck
well, you know that two possibilities are P=(3/8,-3) and Q=(5/8,3)
I assume you can find the slope of PQ.
Luna
How am I supposed to know that the x-values are 3/8 and 5/8?