y1=Asin(WT - KX) y2=Asin(wt + kx)

the resultant of this is y=2AcoskxsimWT

How???and will this resultant is a standing wave??

the principle of superposition states that if two or more waves are passing through a point, the resultant displacement is the sum of the individual displacements,produced independently. Therefore, resultant of y1 and y2 is

A(sin(wt-kx)+sin(wt+kx))=2Acoskxsinwt, this is definitely a standing wave. The amplitude of the wave is a function of 'x' given by 2Acoskx, and the angular frequency of the vibration is equal to w