Arithmetic sequence
a= 26
a4 = 71
a32 = 1.
an = a1 + (n-1)d
a4 = a1 + (3)*d
71 = a1 + (3)*d (I)
a32 = a1 + (31)*d
1 = a1 + 31 d (II)
to find a1 and d we subtract (II)- (I)
1 = a1 + 31 d (II)
-( 71 = a1 + (3)*d) (I)
________________
-70 = 0 28 d
-70 = 28 d
d= -70/ 28
d= -5/2
Replacing d in (I)
71 = a1 - (3)(5/2)
a1= 71 + (3)(5/2)
a1= 78.5
The arithmetic sequence is
an = a1 + (n-1)d
an = 78.5 + 2.5 (n-1)
Verifying
a4 = 78.5 - 2.5 (3) = 78.5 -7.5= 71
a32 = 78.5 +2.5 (31) =78.5 -77.5 = 1
a26 = 78.5 + 2.5 (25) = 78.5 - 62.5 = 16
Give me some minutes
______________________
Answer
a26 = 16
