A = 2x & # 178; + 3ax-2x-1, B = - X & # 178; + AX-1, and the value of 3A + 6b is independent of X, the value of a can be obtained I also want you to explain why it is calculated like this=

A = 2x & # 178; + 3ax-2x-1, B = - X & # 178; + AX-1, and the value of 3A + 6b is independent of X, the value of a can be obtained I also want you to explain why it is calculated like this=

3A + 6B = (15a-6) X-9 has nothing to do with X, even if its coefficient is 0, then 15A = 6