You have $270 in your bank account. You plan to save $80 from your paycheck each week. Which graph shows your bank account balance at the end of each week?
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Answer:
Step-by-step explanation:
We can define the linear function: [tex]y=80x+270[/tex], which model the situation.
One effective and certain way to find the correct graph is graphing the function as it is. For that purpose, we just have to find to points and draw the line. The most common point for a linear function are the interceptions with each axis, that is, when [tex]x=0[/tex] and [tex]y=0[/tex]. For the first case, when [tex]x=0[/tex], we have:
[tex]y=80(0)+270=270[/tex]
For [tex]y=0[/tex], we have:
[tex]0=80x+270[/tex]
[tex]-270=80x[/tex]
[tex]x=\frac{-270}{80}=-3.4[/tex]
So, the interception-axis points are: [tex](0;270)[/tex] and [tex](-3.4;0)[/tex]
The faster way to find the right graph is observing which one has axis-interceptions at his points.
We observe that the first graph has this point as interception:
x-axis interception: [tex](-3.4;0)[/tex]
y-axis interception:[tex](0;270)[/tex]
Therefore, the first graph is the right answer.