Given that$(3x-1)^7=a_7x^7+a_6x^6+a_5x^5+...+a_1x+a_0$, find $a_7+a_6+a_5+a_4+...+a_1+a_0$ Given that$$(3x-1)^7=a_7x^7+a_6x^6+a_5x^5+...+a_1x+a_0$$find $$a_7+a_6+a_5+a_4+...+a_1+a_0$$
Is there anyway to do the question without using binomial theorem and expanding the expression on the LHS??

HINT:
Set $x=1$ to find $\sum_{r=0}^7 a_r=\cdots$
