Question

Arithmetic sequences ; basic algebra please help !

Answer 1

Step-by-step explanation:

an arithmetic sequence means that every new term is the old term plus a constant number.

in our case that constant is +50.

and our starting value a0 = 250

so, the first 4 terms are

$250, $300, $350, $400

for the function formula we know

a0 = $250

a1 = a0 + 50 = 250 + 50 = $300

a2 = a1 + 50 = a0 + 50 + 50 = a0 + 2×50 = $350

a3 = a2 + 50 = a0 + 3×50 = $400

so, we see

an = a0 + n×50 = 250 + 50n

therefore,

f(n) = 250 + 50n

after 9 months saving we reached a9, meaning n=9.

f(9) = 250 + 50×9 = 250 + 450 = $700