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Learn how to evaluate, simplify, add, subtract, and factor algebraic expressions using PEMDAS, distribution property, like terms, linear expressions, and factoring monomials.
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Topic 5 Simplifying expressions and Properties of Operations
7.5.1 algebraic expressions • To evaluate an algebraic expression you replace each variable with its numerical value, then use the order of operations to simplify. • PEMDAS: Parenthesis, exponents, multiplication/division, addition/subtraction
Example 1: w=2 2w = 2*2 = 4 Example 3: n=7 (n+2)2 / 3 = (7+2)2/ 3 = (9)2/ 3 = 81 / 3 = 27 Example 2: p=9 3.3p + 2 = 3.3*9 + 2 = 29.7 + 2 = 31.7
7.5.4 the distributive property • To multiply a sum or difference by a number, multiply each term inside the parentheses by the number outside the parentheses. • a (b + c) = ab + ac • a (b - c) = ab - ac
7.5.5 Simplify Algebraic Expressions • When a plus or minus sign separates an algebraic expression into parts, each part is called a term. • The numerical factor of a term that contains a variable is called the coefficient of the variable. • A term without a variable is called a constant. • Like terms contain the same variables to the same powers, such as 3x2 and 2x2. • An algebraic expression is in simplest form if it has no like terms and no parentheses.
Example 2 • (4x –y)9 = • [4x + (-y)]9 = • (4x)9 + (-y)9 = • 36x + (-9y) = • 36x –9y Example1 5 (x + 3) = 5 · x + 5 · 3 = 5x + 15
7.5.6 Add linear expressions Linear expression: an algebraic expression where the variable is raised to the first power (not square/cubed/etc) and the variables are not multiplied or divided. Examples of linear expressions: • 5x • 3x + 2 • x – 7 Expressions that do not follow these rules are called nonlinear expressions. Examples of nonlinear expressions: • 5mn • 3x3 + 2 • x4 – 7 Directions for completing problems: The plus (positive) sign in between the parentheses means that everything inside the following parenthesis keep the sign it has.
Example1 (5x + 7) + (x + 2) = 5x + 7 + x + 2 = Because we are adding, rewrite without the parentheses 5x + x + 7 + 2 = Rearrange like terms together 6x + 9 Combine like terms Example 2 (– 6x + 3) + (x – 7) = -6x + 3 + x – 7 = Because we are adding, rewrite without the parentheses -6x + x + 3 – 7 = Rearrange like terms together -5x – 4 Combine like terms
7.5.7 Subtract linear expressions • The negative sign before a parenthesis applies to every term inside the following parenthesis. (You must switch the sign of each of the terms inside that next parenthesis.)
Example1 (6x + 7) – (2x + 2) = 6x + 7 – 2x – 2 = Because we are subtracting, switch the sign of each term in the 2nd parenthesis 6x – 2x + 7 – 2 = Rearrange like terms together 4x + 5 Combine like terms Example 2 (2x – 3) – (x – 2) = 2x – 3 – x + 2 = Because we are subtracting, switch the sign of each term in the 2nd parenthesis 2x – x – 3 + 2 = Rearrange like terms together x – 1 Combine like terms
7.5.8 Factor Linear Expressions • A monomial is a number, a variable, or a product of a number and one or more variables. • Monomials: 25, x, 40x • Not monomials: x + 4, 40x + 120 • To factor a number means to write it as a product of its factors. A monomial can be factored using the same method you would use to factor a number. • The GCF (greatest common factor) of two monomials is the greatest monomial that is a factor of both. • Reminder: prime numbers are numbers that can be factored only by 1 and the number itself.
Find the GCF of each pair of monomials Example1 4x, 12x 4x = 2 x 2 xxFind the prime factors of 4x 12x = 2 x 2 x 3 x xFind the prime factors of 12x Find the common factors 2 x 2 x x = 4x Combine the prime factors to find the GCF Example 2 18a, 20ab 18a = 2 x3 xaFind the prime factors of 18a 20ab = 2 x 2 x 5 x a x b Find the prime factors of 20ab Find the common factors 2 x a = 2a Combine the prime factors to find the GCF