Answer
$-6564$
Work Step by Step
Formula to calculate the sum of the first $n$ terms of a geometric sequence is: $s_n=\dfrac{a(1-r^n)}{(1-r)}$
Here, $r=\dfrac{a_2}{a_1}=-3$
As we are given that, $n=7$
Thus, $s_{7}=\dfrac{4 \cdot (-3)(1-(-3)^{7})}{(1+3)}$
or, $s_{7}=-6564$