Algebra: Chapter 9, Lesson 5, page 417.
Inequalities in 2 variables
Given an inequality, treat it as an equality and using the `x` and `y` intercepts, find the solution to the equality. Plot it on your graph paper.
- If the inequality is just a `<`, or `>` problem, then the boundary line (the line you draw connecting the dots) will itself be dotted or dashed. This mean that the points on the line are NOT part of the solution.
- If the inequality has a `≤` or `≥`, then the line will be solid, signifying that the line is part of the solution.
There are 2 ½ planes on the graph, one side of the boundary line that belongs to the solution set (this side will be shaded as part of the solution) and the other side of the line that does not satisfy the inequality.
Now to figure out what ½ plane to shade, pick a point [I like to pick `(0, 0)` or `(1, 1)`] and try those `(x, y)` values in the inequality.
- If the point chosen makes the inequality TRUE, then shade that part of the plane.
- If the point chosen does not satisfy the inequality, then shade the OPPOSITE side ½ plane.
The textbook is actually pretty good in this area, see pages 417-419 for good examples. Purplemath.com has these examples as well.
Two of tonight’s homework problems solved by MrE are here! Just click it
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Algebra: Chapter 7, Lesson 2, page 309
Graphing Equations
(same as yesterday’s lesson – important stuff!)
We can graph an equation, by building a T-chart of values for both x and y. You can choose any values for `x ` and `y` when making your T-chart. I like to use values like 0, 1, and 2. Make them easy and try to pick AT LEAST 3 points when graphing and equation. YOU MUST USE A RULER WHEN CONNECTING THE DOTS TOO!
Sometimes, it can be easier when building the T-chart to “solve for `y`” first, this just cuts down on the workload. Solving for `y` means isolating the `y` variable to one side of the equation and keeping the constants and ALL other variables on the other side.
Here are 2 good links from purplemath.com, the first about graphing in general (lesson 1) and the second about the T-charts and lesson 2!
Two of tonight’s homework problems solved by MrE are here! Just click it