The second derivative of f(x)= √ (x)+3x⁴ is ________.
1) f''(x)=-(1)/(2)x⁽⁻⁽¹⁾/⁽²⁾⁾+36x²
2) f''(x)=(1)/(2)x⁽⁻⁽¹⁾/⁽²⁾⁾+12x³
3) f"(x)=-(1)/(4)x⁽⁻⁽³⁾/⁽²⁾⁾+36x²
4) f"(x)=(1)/(4)