Substitution Property of Equality: Definition & Examples

Substitution Property of Equality

The substitution belongings of equality, one of the 8 houses of equality, states that if x = y, then x may be substituted in for y in any equation, and y may be substituted for x in any equation.

Let’s study a short and easy instance. If we realize that x = y and we’ve got the equation x + five = 7, then we will substitute y for x and write the equation as y + five = 7.

Why is It Important?

In short, the substitution belongings of equality makes algebra possible. If we did now no longer use this belongings in algebra, we’d now no longer be capable of plug in acknowledged values for variables into mathematical expressions and equations. Even eleven though the belongings is quite clean to comprehend, it’s far a huge deal with regards to arithmetic, specifically algebra!

And why is algebra essential, you can ask? Algebra is the department of arithmetic that enables us discover the unknown in a mathematical expression. Usually that ‘unknown’ wide variety might be represented through a letter, like x or y. Algebra is so essential as it lets in us to take actual lifestyles phrase troubles and write them as mathematical expressions in order that we will clear up them.

More details

You’re probable already acquainted with the Transitive Property and the Substitution Property from algebra. If a = b and b = c, then a = c, right? That’s transitivity. And if a = b and b < c, then a < c. That’s substitution. Easy enough. Below, you spot those theorems in extra detail.

Transitive Property (for 3 segments or angles): If segments (or angles) are every congruent to a 3rd segment (or angle), then they’re congruent to every other.

  • The Transitive Property for 3 matters is illustrated within side the above figure.
  • Transitive Property (for 4 segments or angles): If segments (or angles) are congruent to congruent segments (or angles), then they’re congruent to every other
  • Substitution Property: If geometric objects (segments, angles, triangles, or whatever) are congruent and you’ve a declaration concerning one in all them, you may pull the switcheroo and update the only with the alternative. (Note that you’ll now no longer be capable of discover the term “switcheroo” to your geometry glossary.)

Use the Transitive Property because the purpose in a evidence whilst the declaration at the equal line entails congruent matters.


Let’s check a totally easy instance to start. Let’s say that we’ve got fivex and we realize that x = five. We can use the substitution belongings of equality to plug within side the price of x into fivex:

So we’d get five x five, that’s 25!

Example 2:

Let’s study the expression:

4x + fivey + 2p

What is subtraction belongings of equality?

The subtraction belongings of equality tells us that if we subtract from one aspect of an equation, we additionally must subtract from the alternative aspect of the equation to hold the equation the equal. It is the equal with equations. To hold them the equal, you need to do the equal to each facets of the equation.

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