The coefficients corresponding to k = 0, 1, 2, ..., 4 in the expansion of (x + y)4 are
A. 1, 4, 6, 4, 1
B. 1,4,6,6,4,1
C. 0, 1, 4, 6, 4, 1,0
D. 0,4,6,4,0

1/5^2 = 7.56/45

step-by-step explanation:

descending order means to order the polynomials from the term with the largest exponent to the term with the smallest exponent.  

therefore, the correct answer is d.  

47 - 90 = 43

43 - 180 = x

x = 137