1.
If f(x)={sin⁡(a+2x)+sin⁡ax,x<0b,x=0(x+3x2)1/3−x1/3x,x>0f(x) = \begin{cases} \frac{\sin(a+2x) + \sin a}{x}, & x < 0 \\ b, & x = 0 \\ \frac{(x+3x^2)^{1/3} - x^{1/3}}{x}, & x > 0 \end{cases}
is continuous at x=0x = 0, then a+2ba + 2b is equal to