Create equations for the number of scientific and graphical models sold after m months.
After 40 months
Practice makes perfect
First, we have to write equations describing the sale of the different calculators in Slope-Intercept form.
y=mx+b
In this form, m is the slope and b is the y-intercept.
Scientific calculators
The company has already sold 10 000 calculators, which can be interpreted as the function's y-intercept.
b= 10 000
Every month, an additional 1500 calculators are sold. This means that per month the function moves 1500 units in the positive vertical direction. This can be interpreted as a slope of m=1500. Now we can write our function.
y=1500x+10 000
Graphical calculators
Just like when we found the expression for the scientific calculators, we can find an equation for the graphical calculators. The company has sold 18 000 of this model and an additional 1300 every month. With this information, we can write an equation.
y=1300x+18 000
When is the sales equal?
To calculate when the sales of scientific calculators and graphical calculators is equal, we set the right hand side of these equations equal.
10 000+1500m=18 000+1300m
Let's solve it by isolating m on one side of the equation.
