If ddxG(x)=4x3\frac{d}{dx} G(x) = 4x^3dxdG(x)=4x3, which of the following is a valid expression for G(x)G(x)G(x)?
x4+5x^4 + 5x4+5
12x212x^212x2
x3x^3x3
x4+xx^4 + xx4+x