math 180 5.1 – integration 1. we know how to calculate areas of some shapes. 2
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Math 180
5.1 – Integration
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We know how to calculate areas of some shapes.
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Can we find a more general way to figure out areas? Let’s try looking at areas under curves…
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We’ll start by looking at the area under the curve given by from to . Since we don’t have a formula for this area, we’ll use rectangles to estimate the area.
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is an __________, and it always ______________ the true area under the curve.
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is an __________, and it always ______________ the true area under the curve.
maximum
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is an __________, and it always ______________ the true area under the curve.
maximum
upper sum
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is an __________, and it always ______________ the true area under the curve.
maximum
upper sum overestimates
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is a __________, and it always ______________ the true area under the curve.
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is a __________, and it always ______________ the true area under the curve.
minimum
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is a __________, and it always ______________ the true area under the curve.
minimum
lower sum
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When the heights of the rectangles are determined by the _________ function value on each subinterval, our area estimation is a __________, and it always ______________ the true area under the curve.
minimum
lower sum underestimates
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We could also use the midpoint of each subinterval to get the heights of the rectangles:
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Suppose we want to find the distance traveled during a certain time period if we know velocity.
If velocity is constant, we have .
For example, if we travel at 40 mph for 2 hours, then ______________________.
Distance Traveled
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Suppose we want to find the distance traveled during a certain time period if we know velocity.
If velocity is constant, we have .
For example, if we travel at 40 mph for 2 hours, then ______________________.
Distance Traveled
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Suppose we want to find the distance traveled during a certain time period if we know velocity.
If velocity is constant, we have .
For example, if we travel at 40 mph for 2 hours, then ______________________.
Distance Traveled
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Suppose we want to find the distance traveled during a certain time period if we know velocity.
If velocity is constant, we have .
For example, if we travel at 40 mph for 2 hours, then ______________________.
Distance Traveled
(40 mph)(2 hours) = 80 miles
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If velocity is not constant, then there’s no easy formula.
But we can take sample readings of velocity at a bunch of time intervals, and make estimations of the distances traveled on each time interval based on our sample velocities.
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Ex 1.Estimate the distance traveled given the following sample velocities.
Time (s) 0 5 10 15 20 25 30Velocity (ft/s) 25 31 35 43 47 46 41
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We can visualize our calculations on a coordinate system:
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This gives us our first clue that the area under the curve of a function is somehow related to the antiderivative of the function…