Chapter 14: Problem 1
Sketch the described regions of integration. $$0 \leq x \leq 3, \quad 0 \leq y \leq 2 x$$
Short Answer
Expert verified
The region is a triangle with vertices at (0, 0), (3, 0), and (3, 6).
Step by step solution
01
Understand the Region Description
The given region is defined by the inequalities: \(0 \leq x \leq 3\) and \(0 \leq y \leq 2x\). This means \(x\) ranges from 0 to 3, and for each \(x\), \(y\) ranges from 0 to \(2x\).
02
Determine Boundary Lines
Consider the boundary conditions: \(x = 0\), \(x = 3\), and \(y = 2x\). The line \(y = 2x\) is a straight line starting from the origin (0, 0) and having a slope of 2.
03
Sketch the Region
Start by sketching the axes. Plot the line \(x = 3\), which is a vertical line parallel to the y-axis passing through x=3. Next, plot \(y = 2x\), starting from the origin and passing through the point (3, 6) since at \(x = 3\), \(y = 2(3) = 6\). The region is bounded by \(y = 2x\), the x-axis, and the line \(x = 3\).
04
Identify the Bounded Area
Highlight the triangular region which lies below the line \(y = 2x\), to the right of the y-axis (\(x=0\)), and to the left of the line \(x=3\). This region forms a right triangle with vertices at (0, 0), (3, 0), and (3, 6).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Boundary Conditions
Boundary conditions are critical in defining the limits of a region of integration. They determine where the region starts, stops, and outline its limits.
In our exercise, we have two key conditions:
In our exercise, we have two key conditions:
- The range for \(x\) is from 0 to 3. This tells us that the region spans horizontally from the y-axis until it meets the vertical line at \(x=3\).
- The range for \(y\) is from the x-axis (where \(y=0\)) up to the line \(y=2x\). This line dictates the top boundary of our region.
Inequalities
The inequalities \( 0 \leq x \leq 3 \) and \( 0 \leq y \leq 2x \) describe a range of possible values for \(x\) and \(y\).
They tell us something very important:
They tell us something very important:
- \(x\) can be any value between 0 and 3, inclusive.
- For any chosen value of \(x\), \(y\) can vary from 0 to double the \(x\) value (since it goes up to \(2x\)).
Sketching Regions
To visualize a region of integration, sketching is a crucial skill. It transforms abstract inequalities into a visible shape.
Here's how you can tackle it:
Here's how you can tackle it:
- Start by drawing the coordinate axes.
- Mark the vertical line \(x=3\), which sets one side of our region.
- Next, draw the line \(y=2x\), which starts at the origin and passes through the point (3,6).
- Finally, the region consists of the area above \(x=0\), below the line \(y=2x\), and to the left of \(x=3\).
Right Triangle
This exercise identifies a region that forms a right triangle, which is one of the simplest geometrical shapes.
A right triangle has one 90-degree angle, with two sides perpendicular to each other.
A right triangle has one 90-degree angle, with two sides perpendicular to each other.
- In this case, we have vertices at (0,0), (3,0), and (3,6).
- The line \(x=3\) acts as one leg of the triangle, and the segment along the x-axis from (0,0) to (3,0) acts as the other leg.
- The hypotenuse is represented by the line \(y=2x\) from (0,0) to (3,6).