Week 11 – Precalc 11

This week in Precalculas 11  I learned how to graph an inequality. The main difference between inequalities and equations is that equations are equal to 0 and inequalities are not. An inequality can come in many forms and symbols that show the inequality. For example, there is the Greater than symbol >, Less than symbol <, Greater than or equal to symbol ≥, and the Less than or equal to symbol ≤. The symbols determine which part of the graph the answer will be on. If the symbol is equal to and has a line below then it means the point on the graph will be a filled in circle. If it is not equal to then it doesn’t include the point and the circle is not filled in. The other thing we learned this week is how to write answers in interval notation. This is where you use different brackets and symbols to determine what the answer is. For example, if you consider the fact that the lines don’t have domains or ranges and they go on forever if they don’t have a point it would be infinity  (∞), this is only if it’s moving to the right of the number line and is greater than 0. If the lines go on forever but are moving to the left of the number line and is less than 0, then it will be a negative infinity sign ( – ∞). Also when you write in interval notation if the number has a filled in circle and it is equal to then you would use a square bracket, [, ]. If the number is a non – filled circle and is not equal to, you would use round brackets (, ). We also use the round brackets when you are describing the line or parabola with ∞. An example of writing something in interval notation would be (-∞, 5]. Another key note is that if the x is on the smaller end of the symbol x<0 the area that we are focusing on is the inside part of the parabola. If it is the opposite and x>0 then the part we focus on is the outside of the parabola. Another important note is that whenever you are solving an inequality you must always flip the symbol when you divide by a negative.


Leave a Reply