Collecting Like Terms

Polynomials can can be simplified by combining like terms, or terms with the same variables and exponents.

For example, \( a^2b \) and \( -4a^2b\) would be considered like terms and can be combined. To collect the terms, simply add or subtract the coefficients:

Below are some more examples of terms that are like and unlike:

Term Like Term Unlike Term
\(a\) \(3a, -2a, \cfrac{1}{3}a\) \(a^2, \cfrac{1}{a}, \sqrt{a}\)
\(a^2\) \(-5a^2,\cfrac{1}{4}a^2, 0.6a^2\) \(\cfrac{1}{a^2}, \sqrt{a^2}, a^3\)
\(ab\) \(7ab,0.2ab,\cfrac{2}{3}ab,-ab\) \(a^2b,\cfrac{1}{ab}, \sqrt{ab}\)
\(ab^2\) \(4ab^2, \cfrac{ab^2}{7},0.4ab^2,-ab^2\) \(a^2b,ab,\sqrt{ab^2},\cfrac{1}{ab^2}\)


Example

Simplify the expression \((6k - 4) + (2k + 4)\).

We can simplify \( (6k - 4) + (2k + 4) \) using the following steps.

First, we can remove the brackets and identify the like terms:

\(= \textcolor{blue}{6k} - 4 + \textcolor{blue}{2k} + 4 \)

Next, we can identify the like terms and reorder them:

\(= \textcolor{blue}{6k} + \textcolor{blue}{2k} + 4 - 4 \)

Finally, we can collect the like terms:

\(= 8k\)

Therefore, we can determine that the expression simplified is \(\boldsymbol{8k}\).


Simplify the following expressions.

\( (x^2 + 2x + 1) + (2x^2 + 4) \)

First, we can remove the brackets and identify the like terms:

\(\textcolor{blue}{x}^\textcolor{red}{2} + \textcolor{green}{2x} + 1 + \textcolor{blue}{2x}^\textcolor{red}{2} + 4\)

Next, we can identify the like terms and reorder them:

\(\textcolor{blue}{x}^\textcolor{red}{2} +\textcolor{green}{2x}^\textcolor{red}{2} + \textcolor{blue}{2x} + 1 + 4\)

Finally, we can collect the like terms:

\(\textcolor{blue}{3x}^\textcolor{red}{2} + \textcolor{green}{2x} + 5\)

Therefore, we can determine that the expression simplified is \(\boldsymbol{3x^2 + 2x + 5}\).


\( −4x + 3x^2 −7 + 9x- 12x^2 −5x^4 \)

First, we can identify the like terms and reorder them:

\(−5x^{4}+\textcolor{blue}{3x}^\textcolor{red}{2}−\textcolor{blue}{12x}^\textcolor{red}{2}+\textcolor{green}{9x}-\textcolor{green}{4x}−7\)

Finally, we can collect the like terms:

\(−5x^{4} -\textcolor{blue}{9x}^\textcolor{red}{2}+ \textcolor{green}{5x} − 7\)

Therefore, we can determine that the expression simplified is \(\boldsymbol{−5x^{4} - 9x^2 + 5x − 7}\).