Solving Problems Involving APs and GPs (HSC SSCE Mathematics Advanced): Flashcards

$b - a = c - b$

$\frac{b}{a} = \frac{c}{b}$

$b^2 = ac$

Subtraction

Division

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

$T_n = ar^{n-1}$

Small target values, quick answer, calculator available

Large values, exact solution, trial-and-error too long

$2b = a + c$