Pls help me 20 points
1 answer:
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Answer:
12.123
Step-by-step explanation:
You want the area under the curve f(x) = √(3x+5) on the interval [0, 4] estimated using the left sum and four subintervals.
<h3>Riemann sum</h3>When the interval [0, 4] is divided into four equal parts, each has unit width. That means the area of the rectangle defined by the curve and the interval width will be equal to the value of the curve at the left end of the interval.
The area we want is the sum ...
f(0) +f(1) +f(2) +f(3)
As the attachment shows, that sum is ...
area ≈ 12.123 . . . square units
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<em>Additional comment</em>
The table values in the attachment are rounded to 7 decimal places. Trailing zeros are not shown. Actual values used have 12 significant digits, as the total shows.
Such a sum is called a Riemann sum, named for a German mathematician. Four such sums are commonly used, and further refinements are possible. Those are the left sum (as here), the right sum, the midpoint sum, and a sum using a trapezoidal approximation of the rectangle area.
For left, right, and midpoint sums, n function values are required for n subintervals. When the trapezoidal approximation is used, n+1 function values are required.
Answer:
£110
Step-by-step explanation:
We know how much time it takes for a boiler and a radiator, and we need to know how much it will cost for 1 boiler and 4 radiators. We have an initial cost of £30, and since hes doing a boiler - which we know takes an hour - we can already add £20 for a start of £50.
Now, there are 4 radiators, that take 45 minutes each. We need to use this equation:
We divide by 60 because there are 60 minutes in an hour, and he charges by hour. So:
Now, to find out how much to charge, we need to figure out how much to add to the £50. Since it's £20 an hour, and it takes 3 hours to do the 4 radiators, we need to multiply:
Now we add our totals for a grand total of...