U8-U4 = 4d, so d = (65-93)/4 = -7
U1 = U4 - 3d = 93+21 = 114
Un = 114 + (n-1)(-7) = 121 - 7n
Find the nth term and first three terms of the arithmetic squence having U4=93 and U8=65?
2 answers
What about the substitution method