Given:
[tex]\begin{gathered} firstterm(a_1\text{) = -7} \\ \text{common ratio (r) = -4} \end{gathered}[/tex]
Required: First four terms
The nth term of a geometric sequence :
[tex]a_{n\text{ }}=a_1\text{ }\times r^{n-1}[/tex]
Hence, we can obtain the next four terms by substituting
[tex]\begin{gathered} \text{when n = 1, a}_1\text{ = -7} \\ n=2,a_2\text{ =-7 }\times(-4)^{2\text{ - 1}} \\ a_2\text{ = -7 }\times\text{ -4} \\ =\text{ 28} \\ \\ \text{when n =3, a}_3\text{ = -7 }\times(-4)^{3\text{ -1 }} \\ a_3\text{ = -7 }\times\text{ 16} \\ =\text{ -112} \\ \\ \text{when n = 4, a}_4\text{ = }-7\text{ }\times(-4)^{4-1} \\ a_4\text{ = -7 }\times\text{ -64} \\ =\text{ 448} \end{gathered}[/tex]
