A scientific experiment begins with a metal at -100° Celsius. The following function describes the temperature change per minute: f(x) = 89x − 100°.

Question

 How will the graph of this function change if the metal is at 25° at the start of the experiment?

Answer 1

The graph of the original function is a straight line with y-intercept of -100 (which means that it crosses the vertical y-axis at the point (0, -100) and a slope of 89.

The graph of the new function is a straight line with y-intercept of 25 (which means that it crosses the vertical y-axis at the point (0, 25) and a slope of 89.

Hence the slope of line did not change, but the line itself went up by 125 units.

If you use Desmos to graph the original equation y = 89x - 100 and the new equation y = 89x + 25, you will see it.

Answer 2

f(x) = 89x + (starting temperature)

f(x) = 89x + 25