This is a very confusing question, could you please help me solve it?

Write a function that matches the description. a cosine function has a maximum of 5 and a minimum value of -5. f (r) =

Marcus needs to rewrite f(x) = x2 + 6x + 4 in vertex form.

Simplify (4x^2 - 8xy + 2y^2) - (9x^2 - 4xy - 7y^2) a. -5x^2 + 4xy + 9y^2 b. -5x^2 - 4xy + 9y^2 c. -5x^2 + 12xy + 4y^2 d. -5x^2 - 4xy - 5y^2