1. In the expansion of (5a + 7b) n, the sum of the binomial coefficients of each term is equal to 128, then N 2, find the term with the smallest coefficient in the expansion of (a-b) 10 3. The sum of coefficients of each item in the expansion of (a + b) n is 256. Write the binomial coefficients of the expansion in order 4. Find the sum of coefficients of all terms of the expansion of (a-3b) 6 There should be a process. Thank you

1. In the expansion of (5a + 7b) n, the sum of the binomial coefficients of each term is equal to 128, then N 2, find the term with the smallest coefficient in the expansion of (a-b) 10 3. The sum of coefficients of each item in the expansion of (a + b) n is 256. Write the binomial coefficients of the expansion in order 4. Find the sum of coefficients of all terms of the expansion of (a-3b) 6 There should be a process. Thank you

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The sum of binomial coefficients = cN0 + cN1 +... + CNN = 2 to the nth power = 128, the solution is: n = 7, the square of n = 49, the general term of coefficient of (a-b) 10 is | c10r * 1 (10-r) * (- 1) r | = c10r, when R is odd, the term is negative, when R is odd and c10r is maximum, the term is the minimum term of coefficient