9514 1404 393
Answer:
A. 40, dollars added per day to the bank account
B. y -600 = 40(x -0); y = 40x +600; 40x -y = -600
C. f(x) = 40x +600
D. $880
Step-by-step explanation:
A. The slope is given by the formula ...
m = (y2 -y1)/(x2 -x1)
m = (720 -600)/(3 -0) = 120/3
m = 40
The bank account is increasing at the rate of $40 per day.
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B. Point-slope form is ...
y -k = m(x -h) . . . . . line with slope m through point (h, k)
Using the first point, we have (h, k) = (0, 600) and m = 40.
y -600 = 40(x -0)
Slope-intercept form is ...
y = mx +b . . . . . . line with slope m and y-intercept b
The first point tells us the y-intercept is b=600, so the equation is ...
y = 40x +600
Standard form is ...
ax + by = c . . . . . . . a > 0, and a, b, c mutually prime
This form can be obtained by subtracting y from the point-slope form.
40x -y = -600
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C. Replacing y with f(x) in the slope-intercept form gets the desired equation.
f(x) = 40x +600
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D. The table shows the balance after 6 days. The balance increases $40 each day, so the balance after 7 days is ...
$840 +40 = $880 . . . . balance after 7 days
