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What algebraic property is used to show that if x+5 = 15, then x=10?

User Ferhrosa
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1 Answer

16 votes
16 votes

The algebraic property is that of addition property of an equality.

Although we refer to "addition" in general because you may be "adding" a negative number to both sides of the equation, like in this case

Yourneed to add on both sides the "opposite" of "5" (-5) in order to get rid (eliminate) the numerical term "5" that is adding to x. That way leaving x on its own on one side of the equal sign.

For what I see your teacher has the addition of an opposite defined as subtraction property of equality. So you should mark that one.

With multiplication and division something similar happens. They are both grouped under multiplication property of equality, because you are multiplying by the reciprocal of the factor that accompanies the term in "x".

So, the division is normally interpreted as a form of multiplication. But if your teacher has it separate as "division", you should mark the specific division.

User Ceco
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