F(-3)=5-(x-2)^2

Please answer :)

Use set buikder notation to represent the following set: {, -2, -1, 0}

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

I’m stuck on this equation, anyone got the answer?