If a store is selling packs of gum at 3 for $0.99, how much would 12 packs cost?
2 answers:
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Answer:
Step-by-step explanation:
Let the x-axis be the time (in years) and the y-axis the value of the fax machine (in dollars).
We know that the initial value of the fax machine is $100; in other words, when the time is zero years, the value is $100, or as an ordered pair (0, 100). We also know that after 1 year the value decreases to $80, so (1, 80).
Now we can find the slope of the line passing through those two points using the slope formula
where
is the slope
are the coordinates of the first point
are the coordinates of the second point
Replacing values:
Now, to complete our model we are using the point slope formula
where
is the slope
are the coordinates of the first point
Replacing values:
We can conclude that the correct linear depreciation model is
y = - x - 34
the equation of a line in slope-intercept form is
y = mx + c ( m is the slope and c the y-intercept )
to calculate m use the gradient formula
m = ( y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁ ) = (- 68, 0 ) and (x₂, y₂ ) = (0, - 34 )
m = =
= -
the y-intercept = (0, - 34 ) ⇒ c = - 34
y= - x - 34