(3x-1)^7, then addition of all cofactors is =?

Question :(3x-1)⁷, then addition of all cofactors is =? if cofactors are A7,A6,A5,A4,A3,A2,A1,A0

Solution

1.       3x-1=3x-1

2.       (3x-1)²=9x²−6x+1

3.       (3x-1)³=27x³−27x²+9x−1

4.       (3x-1)⁴=81x⁴−108x³+54x²−12x+1

5.       (3x-1)⁵ =243x⁵−405x⁴+270x³−90x²+15x−1

6.       (3x-1)⁶ =729x⁶−1458x⁵+1215x⁴−540x³+135x²−18x+1

7.       (3x-1)⁷ =2187x⁷−5103x⁶+5103x⁵−2835x⁴+945x³−189x²+21x−1
  Key to answer :Addition of An,A(n-1),A(n-2).............A0=2^n

Algebra	Cofactors for the algebraic expression (3x-1)7
	A7		A6	A5	A4	A3		A2	A1	A0	Total
3x-1									3	-1	2
(3x-1)2								9	-6	1	4
(3x-1)3							27	-27	9	-1	8
(3x-1)4					81		-108	54	-12	1	16
(3x-1)5				243	-405		270	-90	15	-1	32
(3x-1)6		729		-1458	1215		-540	135	-18	1	64
(3x-1)7	2187	-5103		5103	-2835		945	-189	21	-1	128