Explanation:
I cannot see all the answer options.
square garden, side length x.
area = x² (or x×x)
new area r = (x-p)(x+q) = x² - px + qx - pq =
= x² + (q - p)x - pq
3D printer. costs p in general.
makes x figurines.
material per figurine costs q.
costs per figurine r = q + p/x
as the printer costs themselves need to be distributed equally across all produced figurines.
investment account. q% pretty year.
p dollars starting balance.
letting it sit for x years.
a0 = p
a1 = a0 + a0×q/100 = a0 × (1 + q/100)
a2 = a1 + a1×q/100 = a1×(1 + q/100) = a0×(1 + q/100)²
a3 = a2 + a2×q/100 = a2×(1 + q/100) = a0×(1 + q/100)³
...
ax = a0×(1 + q/100) to the power of x =
= p × (1 + q/100) to the power of x
account without interest. p dollars are already in it.
adding q dollars every month for x months.
balance after these x months
r = x×q + p = q×x + p