Answer:
f(x) = 3x + 8 is the required linear function.
Step-by-step explanation:
We know that the slope-intercept form of linear equation is
y = mx+b
here
Given initial value
f(0) = 8
Thus, the y-intercept = b = 8
Also given
at x = 4, f(4) = 20
so
substituting the point (4, 20) and y-intercept b=8 in the slope-intercept form to determine the slope
y = mx+b
20 = m(4) + 8
20 = 4m + 8
4m = 20-8
4m = 12
Dividing both sides by 4
m = 3
Thus, the slope = m = 3
Now, substituting m = 3 and b = 8 in the slope-intercept of linear function
y = mx+b
y = 3x + 8
or
f(x) = 3x + 8
Thus,
f(x) = 3x + 8 is the required linear function.
VERIFICATION:
Given the linear function
f(x) = 3x + 8
plug in x = 0
f(0) = 3(0) + 8
f(0) = 8
plug in x = 4
f(x) = 3x + 8
f(4) = 3(4) + 8
f(4) = 12+8
f(4) = 20