Finding the Values of a and d (Leaving Cert Mathematics): Flashcards

$T_n = a + (n-1)d$

First term of the sequence

Common difference

The nth term

Position of the term

Write down the general term formula for each given term

$d$ first, then $a$

Subtract one equation from the other

Common difference must be same: $T_2 - T_1 = T_3 - T_2$

Forgetting the $(n-1)$

Substitute values back into the original given terms

To solve for two unknowns ($a$ and $d$)