Answer:
a) 3.5 cm / month
b y = 3.5(x-1) + 4, x >= 1
Step-by-step explanation:
the plant grew 32-4 = 28 cm in 9-1 = 8 months.
so, the growth rate is 28 cm / 8 months = 7 cm / 2 months, or (to norm it to a typical 1 unit denominator) 3.5 cm per month.
x = months of growth
y = height of plant
so, considering the "start" of 4 cm after one month, the equation is
y = 3.5(x-1) + 4, x >= 1
since we don't know anything about anything that happened before the first month was over, we cannot validate this equation for anything x<1.