Answer to Question #316372 in Algebra for Fish

Question

The first term,seventh term and nth term of an AP are 4, 28 and 32 respectively. Calculate the number of terms in the sequence.

Answer 1

$a_n=a_1+(n-1)d.$

$a_1=4.$

$a_7=a_1+(7-1)d\to 28=4+6d\to d=4.$

$a_n=4+4(n-1) \to 32=4+4(n-1) \to n=8.$

There are 8 terms in the sequence.