How to add and subtract similar monomials?

Adding and subtracting similar monomials rule

When adding and subtracting similar monomials we only add or subtract the coefficients of the monomials.

See the definition of similar monomials.

Example of adding and subtracting of similar monomials.

Add and subtract the monomials

9n + 5n - 12n

Solution.

The coefficients of the monomials are 9, 5 and 12.

9n + 5n - 12n = 2n

The answer: 2n.

Example of adding and subtracting of similar monomials.

Add and subtract the following monomials

21.5b + 5.5b - 4.5b

Solution.

The coefficients of the monomials are 21.5, 5.5 and 4.5.

21.5b + 5.5b - 4.5b =

22.5b

22.5b

The answer: 22.5b.

Example of adding and subtracting of similar monomials.

Adding and subtracting similar monomials

5gh + 4.7gh - gh

Solution.

5gh + 4.7gh - gh =

5gh + 4.7gh - 1gh

5gh + 4.7gh - 1gh

The coefficients of the monomials are 5, 4.7 and 1.

5gh + 4.7gh - gh =

5gh + 4.7gh - 1gh = 8.7gh

5gh + 4.7gh - 1gh = 8.7gh

The answer: 8.7gh.

Example of adding and subtracting of similar monomials.

Add and subtract the following monomials

45k^{4} + 5k^{4} - 3m^{3}

Solution.

Are all these three terms similar monomials? No, they are not.

Only the two monomials 45k^{4} and 5k^{4} are similar monomials.

The coefficients of the similar monomials are 45 and 5.

45k^{4} + 5k^{4} - 3m^{3} =

(45k^{4} + 5k^{4}) - 3m^{3} =

50k^{4} - 3m^{3}

(45k

50k

The answer: 50k^{4} - 3m^{3}.