help me to solve it

Problem 0. Generate two signals with a length of 200, x1=sin(2*pi*10*t)+randn1(1, 200) and x2=2sin(2pi*5*t)+randn2(1, 200), where t=[0:99]/100. (randn1 and randn2 are two different random noises generated by randn.) ~ a) Describe the main features of the autocorrelation coefficients and the cross-correlation of the two functions; b) Plot the above three coefficients in Matlab.