I need help!! Please solve theses using formulas and please explain.

Answer:
[tex]4 \times - 2 {}^{n - 1} [/tex]
Step-by-step explanation:
Use the formula.
[tex]f(n) = f(1) \times {r}^{n - 1} [/tex]
where f(1) is the first terms, r is the common ratio, and n is our undefined term.
4 is our first term. so
f(1)=4.
Our common ratio is -2 so
r=-2.
[tex]4 \times - 2 {}^{n - 1} [/tex]