Does the graph represent a function ?

Factor this polynomial completely x^2-64

Marla bought a book for $12.95, a binder for $3.49, and a backpack for $44.99. the sales tax rate is 6%. find the amount of tax and the total she paid for these items

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'