The 28 term of an ap is -5, find the common difference if its 1st term is 31
28t=a+27d
since 28t=-5 ,a=31
-5=31+27d
-27d=31+5
-27d=36
d=-36/27
d=-4/3
or, using your definitions:
term(28) = a + 27d = -5 , but a = 31
31 + 27d = -5
27d = -36
d = -36/27 = - 4/3
27 differences (1st to 28th)
common difference = (-5 - 31) / 27
Thank you very much
thanks
T28=6+(28-1)d
6+(27)5
6+135
141
T28=a+(n-4)d
-5=31+(28-1)d
-5=31+27d
Collect like terms
27d=-5-31
27d=-36
D =-36/27
D=-4/3