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Topic 2/3
15 Flashcards in this deck.
In algebra, like terms are terms that have identical variables raised to the same power. They differ only in their coefficients. For example, in the expression $3x^2 + 5x - 2x^2 + 7$, the terms $3x^2$ and $-2x^2$ are like terms, while $5x$ and $7$ are not like terms with $x^2$ or each other.
Combining like terms simplifies algebraic expressions, making them easier to work with. This simplification is crucial when solving equations, factoring, and performing other algebraic operations. It reduces complexity and helps in identifying patterns and relationships within mathematical problems.
Consider the expression $4y + 3y - 2 + 5$. Here, $4y$ and $3y$ are like terms, and $-2$ and $5$ are constant terms that can also be combined.
Combining the like terms:
$$ 4y + 3y = 7y $$ $$ -2 + 5 = 3 $$So, the simplified expression is:
$$ 7y + 3 $$When variables are raised to powers, only terms with the same variable and exponent are considered like terms. For example, $2x^3 + 5x^2 - x^3 + 4x^2$ can be simplified by combining like terms as follows:
$$ 2x^3 - x^3 = x^3 $$ $$ 5x^2 + 4x^2 = 9x^2 $$The simplified expression is:
$$ x^3 + 9x^2 $$In expressions with multiple variables, like terms must have the same variables raised to the same powers in the same order. For example, $3ab + 2a b - ab + 4ac$ combines the terms with $ab$.
Combining the like terms:
$$ 3ab + 2ab - ab = 4ab $$The term $4ac$ remains unchanged as it does not have the same variable components as $ab$.
The simplified expression is:
$$ 4ab + 4ac $$The distributive property can be used to simplify expressions before combining like terms. For instance, consider the expression $2(x + 3) + 4x$.
First, apply the distributive property:
$$ 2x + 6 + 4x $$Now, combine like terms:
$$ 2x + 4x = 6x $$ $$ 6 $$The simplified expression is:
$$ 6x + 6 $$Polynomials often require combining like terms to simplify. For example, in the polynomial $5x^4 - 3x^2 + 2x^4 + x^2 - 7$, combine the $x^4$ and $x^2$ terms separately.
Combining like terms:
$$ 5x^4 + 2x^4 = 7x^4 $$ $$ -3x^2 + x^2 = -2x^2 $$The simplified polynomial is:
$$ 7x^4 - 2x^2 - 7 $$Simplify $7m + 3n - 2m + 5n$:
$7m - 2m = 5m$Result:
$$5m + 8n$$Combine like terms in $4x^2 + 5x - 3x^2 + 2x - 8$:
$4x^2 - 3x^2 = x^2$Result:
$$x^2 + 7x - 8$$Simplify $6ab - 2ac + 4ab + 3ac$:
$6ab + 4ab = 10ab$Result:
$$10ab + ac$$Combine the terms $9y^3 + 2y^2 - y^3 + 4y^2$:
$9y^3 - y^3 = 8y^3$Result:
$$8y^3 + 6y^2$$Aspect | Description | Example |
Like Terms | Terms with identical variable parts and exponents. | $4x^2$ and $-2x^2$ |
Unlike Terms | Terms with different variables or exponents. | $3x$ and $5y$ |
Combining Process | Adding or subtracting coefficients of like terms. | $3x + 2x = 5x$ |
Distributive Property | Expanding expressions to identify like terms. | $2(x + 3) = 2x + 6$ |
Common Mistakes | Mismatching variables, ignoring negative signs. | Incorrect: $3x + 4y = 7xy$ |
To master combining like terms, always line up similar variables and their exponents before adding or subtracting coefficients. A helpful mnemonic is "Same Variable, Same Power, Combine Every Hour," reminding you to check both the variable and its exponent. Practice consistently with diverse problems to build proficiency. For exam success, double-check your work by re-identifying like terms and ensuring all coefficients have been accurately combined.
Combining like terms is not just a fundamental algebraic skill but also underpins many real-world applications. For instance, in computer graphics, simplifying expressions efficiently allows for smoother rendering of images. Additionally, the principles of combining like terms are used in chemical equations to balance reactions, ensuring the law of conservation of mass is maintained.
Students often confuse unlike terms when combining, leading to incorrect simplifications. For example, mistakenly combining $3x$ and $3y$ as $6xy$ is incorrect because the variables differ. Another common error is neglecting to distribute negative signs properly, turning $-2(x + 3)$ into $-2x + 3$ instead of the correct $-2x - 6$. Additionally, overlooking constants and trying to combine them with variable terms can result in errors like $5x + 3 = 8x$ instead of recognizing that $5x + 3$ cannot be simplified further.