A cosine function has a period of 3, a maximum value of 20, and a minimum value of 0. The function is a reflection of its parent function over the x-axis.

Question

Which function could be the function described?

f(x)=10cos(3x)−10

f(x)=10cos(2π3x)+10 <my choice

f(x)=−10cos(2π3x)+10

f(x)=−10cos(3x)+10

Answer 1

where did you learn to write fractions? 2π/3 is the way to write it.

However, your choice is not quite correct. You forgot the reflection part. So, the correct answer is

f(x) = −10cos(2π/3 x)+10

-10cos(2π/3 x) has max/min at 10,-10 and is a reflection of cos(2π/3 x)

Now add 10 and you get max/min at 20,0