Question

What is the sum of the geometric sequence -4, 24, -144, ... if there are 7 terms

Answer 1

I keep getting 223948...

Answer 2

sum of gp series when n ie no of terms are finite::
\[S=a(1-r ^{n}/1-r) when r<1\]
and \[S=a(r ^{n}-1)/(r-1) \] when r>1

Answer 3

a -first term of sequence
r-common ratio

Answer 4

This is my equation = -4 + 4(-6)^7/1 + 4

Answer 5

here r=-6 and a=-4

Answer 6

\[(-4)(1-(-6)^{7})/(1-(-6))\]
(-4)((1-(-279936))/(7))
(-4)*((279937)/7)
-159964

Answer 7

oh my god. i replaced the bottom with -4 instead of 7. Thanks i see what i did

Answer 8

@mukushla can you please check it

Answer 9

sorry i was busy
Quite Right..