A parent increases a child’s monthly allowance by 20% each year. If the allowance is $8 per month now. This is an exponential function, An exponential function is given by:
Let x be the number of years and y be the allowance. The initial allowance is $8, this means at x = 0, y = 8
Since it increases by 20% each year, i.e 100% + 20% = 1 + 0.2 = 1.2. This means that b = 1.2 Therefore:
To find the number of years will it take to reach $20 per month, we substitute y = 20 and find x
