The advantage of the graphing calculator is that you just have to find two independent equations, introduce them in the calculator and it will find the intersection point ot the two graphs.
The equations that you have to introduce are:
1) y = 2.25x + 24
2) y = 2.75x + 23
The algebraic solution, which will give you the same coordinates of the intersection point of the graphs is
2.25x + 24 = 2.75x + 23
2.75x - 2.25x = 24 - 23
0.5x = 1 => x 1 /0.5 = 2.
Answer: 2
6 years
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
x = 6 years to the nearest year