1.

Which term of an AP 20,19[1/4],18[1/2], 17[3/4],... is the first negative term?

Answer» `20,77/4,37/2,71/4,.....`
`d=77/4-20=3/4`
`d=(77-80)/4=-3/4`
Let,` a_r<0`
`a+(r-1)d<0`
`20+(r-1)(-3/4)<0`
`(r-1)(3/4)>20`
`(r-1)>80/3`
`r>83/3`
`r=28`
28th term.


Discussion

No Comment Found