Prove that cos( = − 1 for any real number

If you could answer these your a life saver

When is g(x) = 0 for the function g(x) = 5.23x + 4?

For which pairs of functions is (f•g)(x)=12x? f(x)=3-4x and g(x)=16x-3 f(x)=6x2 and g(x)= 2/x f(x)= and g(x) = 144x f(x)=4x and g(x) =3x