Check these please?
@Michele_Laino
from the general theory, we can write this: \[\frac{{140}}{{35}} = \frac{1}{{{q^2}}}\] where \(q\) is the constant of the sequence. Please solve for \(q\)
How do you pronounce your name? @Michele_Laino
q=1/2,-1/2
my name is equivalent to "Michael"
ok! the possible values of \(q\) are correct!
Oh good! That's what I have been calling you the whole time! x :)
Sweet, so what now?
now, we have to compute the first term of the sequence. In order to do that, we can write this: \[35 = {a_1}{q^6} = \frac{{{a_1}}}{{64}}\] please solve for \(a_1\)
Wait, Michele, how did you get that?
since, from the general theory, we have: \[{a_7} = {a_1}{q^{\left( {7 - 1} \right)}}\]
I got the first and second one! Hey Michele how about the 3rd one? aye?
Oh, duh. Sorry, brain fart :P
I think that we have to apply this formula: \[{S_{10}} = {a_1}\frac{{1 - {q^{10}}}}{{1 - q}} = 1 \cdot \frac{{1 - {4^{10}}}}{{1 - 4}} = ...?\] which comes from the general theory about geometric sequences
349525 awesome thinking!
that's right!
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