Question 133104
Notice how each term is cut in half and is negated (ie the sign is changed). In other words, each term is multiplied by {{{-1/2}}}


Cut the 1st term 80 in half and negate it to get –40. In other words, {{{(80)(-1/2)=-40}}}


Cut the 2nd term –40 in half and negate it to get 20. In other words, {{{(-40)(-1/2)=20}}}


Cut the 3rd term 20 in half and negate it to get –10. In other words, {{{(20)(-1/2)=-10}}}


Cut the 4th term –10 in half and negate it to get 5. In other words, {{{(-10)(-1/2)=5}}}


 
So to find the next two terms, simply multiply the last few terms by {{{-1/2}}}



So lets multiply the last term 5 by {{{-1/2}}}


{{{5(-1/2)=-5/2}}}


So the next term is {{{-5/2}}} or -2.5



Now lets multiply the last term {{{-5/2}}} by {{{-1/2}}}


{{{(-5/2)(-1/2)=5/4}}}


So the next term is {{{5/4}}} or 1.25




So the updated sequence is 


80, –40, 20, –10, 5, {{{-5/2}}}, {{{5/4}}}