There is one very important exception to the rule that multiplying or dividing an inequality is the same as multiplying or dividing an equation. Whenever you multiply or divide an inequality by a negative number, you must flip the inequality sign. One very important implication of this rule is: You cannot divide by an unknown i. There are plenty of instances where you will know the sign of a variable and as a result, you can multiply or divide and know for sure whether you must flip the inequality sign.
Standard Form of a Linear Equation. How to Solve Inequalities With Fractions. How to Divide Negative Numbers. How to Determine Linear Equations. How to Do Math Problems in Algebra 1. How to Calculate the Equation of a Line. How to Solve Absolute Value Inequalities. How to Find the Domain of a Function Defined by an How to Compare Negative Fractions.
How to Solve for a Variable. How to Get the Value of a Letter in Algebra 1. How to Find the Zeros of a Function. Add a comment. Active Oldest Votes. Seeing why 1 is true is not too hard.
The other cases can be handled similarly. But, perhaps a bit of rigor is needed here. David Mitra David Mitra Either it is circular or so incomplete to be of little help. Alas, the OP doesn't know what he's missing by accepting it. Perhaps you may wish to do him a favor by improving the answer. However, after reading your answer it appears the short and straight answer is because of law of signs which I think is what I was looking for.
The reason that the reversal for equality escapes notice is that the symbol for equality is symmetric. Dave L. Renfro Dave L. Renfro Bill Dubuque Bill Dubuque k 36 36 gold badges silver badges bronze badges. At its essence it is a law of an ordered field. Mark Mark 5, 28 28 silver badges 29 29 bronze badges. Larry B. Ali Ali 11 1 1 bronze badge. Upcoming Events.
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