bertramjeratire

 

[tex]b_{n}=b_{1} \times {q}^{n-1}[/tex]

[tex]b_{4}=32 \times (-\frac{1}{2})^{(4-1)}\\b_{4}=32 \times (-\frac{1}{2})^{3}\\b_{4}=32 \times (- \frac{1}{8})\\b_{4}=-4[/tex]