Question: expansion in powers of x

Hi all,

I am stuck in a question. Perhaps somebody can help me. I have to find the values for a, b, c and d such that the expansion of y in powers of x, does not contain the term of x^p for p=3,4,5,6. 

I defined y:

restart:
y:=[(1+a*x+b*x^2)/(1+c*x+d*x^2)]*ln(sinh(x)^2 + cosh(x)^2);

 

But now it became terrible. I tried: series(ln(sinh(x)^2 + cosh(x)^2), x=0, 10). I think I am not right. Can somebody please help me?

Please Wait...