Question

Срочно❤️​❤️❤️❤️❤️❤️​

Answer 1

1)

b1=/125 q=5

b4-? b7-?

$b_{n} =b1*q^{n-1}$

$b4=\frac{1}{125} *5^{4-1} =\frac{1}{125}*125=1\\b7=\frac{1}{125} *5^{7-1} =\frac{1}{125}*15625=125$

2)

b1=15 q=2/3

S3-?

$S_{3} =\frac{b_{1}*(q^{3} -1)}{q-1} \\\\S_{3} =\frac{15 *(\frac{2}{3} ^{3} -1)}{\frac{2}{3} -1}=\frac{15*\frac{8}{27} }{-\frac{1}{3} } =\frac{40}{9} *-3=-\frac{40}{3} =-13\frac{1}{3}$