a.
n=1 is -4*1=-4
1st term is -4
2nd is -4/3
3rd is -4/9
4th is -4/27
b. converge because -1<r<1
c. as long as -1<r<1, then
the sum of the infnite series is
[tex] \frac{a_1}{1-r} [/tex]
a1=-4
r=1/3
[tex] \frac{-4}{1-1/3} [/tex]=[tex] \frac{-4}{2/3} [/tex]=-12/2=-6
it has a sum of -6
sum of gemoetric sequence is
[tex] \frac{a_1(1-r^n)}{1-r} [/tex]
a1=6
r=2
n=10
[tex] \frac{6(1-2^{10})}{1-2} [/tex]
[tex] \frac{6(1-2^{10})}{-1} [/tex]
6138
2nd answer
3*5+4*5+5*5+6*5+7*5+8*5=
5*(3+4+5+6+7+8)=
165
answer is 4th one
