PLEASE HELP!!!!!! 20 POINTS!!!!!

Mathematics

1 answer:

Advocard [28]2 years ago

5 0

Answer:

-18.703

Step-by-step explanation:

a₁=-28(-1/2)¹⁻¹

r=-1/2

a₁=-28

r=-1/2

S₉=a₁ $\frac{1-r^{9} }{1-r}$

S₉=-28 $\frac{1-(\frac{1}{2})^{9} }{1-(\frac{1}{2}) }$

S₉= $-\frac{1197}{64}$

S₉=-18 $\frac{45}{64}$ S₉=-18.703125

You might be interested in

(1/4)^3z-1 =16^z+2*64^z-2<br><br> Z=___<br><br> Please help

wariber [46]

Answer:

Z = 0.198877274

Step-by-step explanation:

$(\frac{1}{4})^{3z-1} = 16^z + 2*16^{z-2}\\4^{1-3z} = 4^{2z} + 4^{\frac{1}{2}}*4^{2z-4}\\4^{1-3z} = 4^{2z} + 4^{2z-4+\frac{1}{2}}\\4^{1-3z} = 4^{2z} + 4^{2z-\frac{7}{2}}\\4^{1-3z} = 4^{2z} *(1+ 4^{-\frac{7}{2}})\\4^{1-3z} = 4^{2z} *(1+ 2^{-7})\\4^{1-3z} = 4^{2z} *(1+ \frac{1}{128} )\\4^{1-3z} = 4^{2z} *(\frac{129}{128} )\\Taking\;\; Logarithm\;\; with\;\; base\;\; 4\\Log_4(4^{1-3z}) = Log_4(4^{2z}) + Log_4(\frac{129}{128})\\1-3z = 2z + 0.005613627712 \\5z = 0.994386372\\z = 0.198877274$