Dave started playing his Nintendo 3DS while it was at 100%. After 4 hours his batter was at 20%. Let B represent his battery % while h represents the number of hours he's been playing.
A) Find the slope of the battery %.
B) Find the y intercept in the slope intercept equation, and what does it mean in this problem?
C) Write a linear equation in the slope intercept form for the 3DS's battery percentage.
D) Using the equation from part C, find the h intercept to show the decline of the 3DS's battery.
A) Find the slope of the battery %.
B) Find the y intercept in the slope intercept equation, and what does it mean in this problem?
C) Write a linear equation in the slope intercept form for the 3DS's battery percentage.
D) Using the equation from part C, find the h intercept to show the decline of the 3DS's battery.
A) Using B for the battery % and h for the number of hours Dave has been playing to write the equation.
Dave loses 20% battery life every hour he plays.
C) In this equation above, B is the y intercept and h is the x intercept. Therefore B1 is the initial y intercept, which is 100. In this equation y2, represents 100% of the 3DS's battery life when Dave started playing.
Using what we already know, from the other parts of this problem, we can now substitute our numbers into the slope intercept equation y=mx+b, or in this instance, B=mh+b.
B=-20h+100
B=-20h+100
D) Plot the h intercept starting with 0 to show when Dave started playing, and continue through 14 hours to show when the 3DS will die.
Reflection
When dealing with a negative slope in the slope intercept equation y=mx+b, m must be a negative number. This is because when working with a negative slope, the line on the graph falls from left to right, resulting in a negative slope. When graphing coordinates (x,y) you have to have an understanding of which axis belongs to which coordinate. When looking at a graph the horizontal axis is x, whereas the vertical axis is y. In order to plot a line however, you need 2 coordinates to connect. In the case of negative slopes, you need 2 coordinates that when connected, the line falls from left to right. When you have an equation such as y=-3x+6, -3 is the slope, whereas 6 is the y intercept. With just this equation along you can plot 2 points. Since 6 is your y intercept, you would plot it on the point (0,6). From there since the slope is -3, you would fall 3 coordinates, and right 1, for a new coordinate of (1,3).