I need help on this practice question ​

Sketch one cycle if the cosine function y=2cos2theta

Y=(x+3)(x-4)(x+1)^2 sulutions? multiplicity?

Hell . what are the solutions to `10x^2 - 38x - 8 = 0`? is this when i find the factors and use the numbers within the factors to determine the zeros? i hope that made sense lol