Answer:
x = 36
Step-by-step explanation:
Subtract x and 36 from both sides.
Divide both sides by -1.
Square both sides.
Subtract 144x from both sides.
Factor the right side.
Since the solution of the equation involved squaring both sides, we musty check the answer for possible extraneous solutions.
Check x = 36:
Since 0 = 0 is a true statement, the solution x = 36 is a valid solution.
The initial fee of $50 is essentially the y intercept because this is the value when x = 0 (x is the number of labor-hours). So b = 50.
The slope is m = 30 because each increase of 1 hour leads to the cost bumping up by 30 dollars. In other words, slope = rise/run = (change in cost)/(change in hours) = 30/1
So we plug m = 30 and b = 50 into the y = mx+b formula to get y = 30x+50
Replace y with f(x) to get f(x) = 30x+50
The linear function for the cost is f(x) = 30x+50
Note: Some books may use other letters (instead of x and f(x)), but the idea is still the same
Once you know the cost function, you replace x with 4.5 to find the amount it will cost to have a painter work for 4.5 hours.
f(x) = 30x+50
f(4.5) = 30*4.5+50
f(4.5) = 135+50
f(4.5) = 185
It will cost 185 dollars to have the painter work for 4.5 hours
The first and last choices are true.
