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OpenStax books

Prealgebra 2e

A short summary of each chapter, then the key terms that chapter names. Each chapter link opens that chapter in the OpenStax book.

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Chapter 1

Whole Numbers

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Summary

All digits to the left of that place value do not change unless the given place value is a 9, in which case it may. Underline the digit to the right of the given place value If yes—add 1 to the digit in the given place value. Use commas in the number to separate the periods

Key terms

whole numbers
The whole numbers are the numbers 0, 1, 2, 3, …
given place value
a 9, in which case it may
number line
A number line is used to visualize numbers. The numbers on the number line get larger as they go from left to right, and smaller as they go from right to left
place value system
Our number system is called a place value system because the value of a digit depends on its position, or place, in a number
coordinate
A number paired with a point on a number line is called the coordinate of the point
divisor
When dividing two numbers, the divisor is the number dividing the dividend
dividend
When dividing two numbers, the dividend is the number being divided
difference
The difference is the result of subtracting two or more numbers

Chapter 2

The Language of Algebra

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Summary

The expression of a n is read a to the n th power Order of Operations When simplifying mathematical expressions perform the operations in the following order Equality Symbol a = b is read as a is equal to b

Key terms

expressions
An expression is a number, a variable, or a combination of numbers and variables and operation symbols
expression of a n
read a to the n th power
solution of an equation
A solution to an equation is a value of a variable that makes a true statement when substituted into the equation. The process of finding the solution to an equation is called…
like terms
Terms that are either constants or have the same variables with the same exponents are like terms
least common multiple
The smallest number that is a multiple of two numbers is called the least common multiple (LCM)
prime factorization
The prime factorization of a number is the product of prime numbers that equals the number

Chapter 3

Integers

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Summary

Addition of Positive and Negative Integers 5 + 3 -5 + ( -3 ) both positive, sum positive both negative, sum negative When the signs are the same, the counters would be all the same color, so add them. Opposite Notation - a means the opposite of the number a The notation - a is read the opposite of a Absolute Value Notation The absolute value of a number n is written as | n |

Key terms

integers
Integers are counting numbers, their opposites, and zero ... -3, -2, -1, 0, 1, 2, 3
absolute value
The absolute value of a number is its distance from 0 on the number line
signs
the same, the counters would be all the same color, so add them
opposites
The opposite of a number is the number that is the same distance from zero on the number line, but on the opposite side of zero
negative number
A negative number is less than zero

Chapter 4

Fractions

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Summary

Proper and Improper Fractions The fraction a b is a proper fraction if a < b and an improper fraction if a ≥ b Mixed Numbers A mixed number consists of a whole number a and a fraction b c where c ≠ 0 Equivalent Fractions Property If a, b, and c are numbers where b ≠ 0 , c ≠ 0 , then a b = a ⋅ c b ⋅ c Write the mixed number as quotient remainder divisor

Key terms

fraction
A fraction is written a b . In a fraction, a is the numerator and b is the denominator. A fraction represents parts of a whole. The denominator b is the number of equal parts the…
mixed number
A mixed number consists of a whole number a and a fraction b c where c ≠ 0 . It is written as a b c , where c ≠ 0
equivalent fractions
Equivalent fractions are two or more fractions that have the same value
proper and improper fractions
The fraction a b is proper if a < b and improper if a ≥ b
fraction a b
a proper fraction if a < b and an improper fraction if a ≥ b
least common denominator (LCD)
The least common denominator (LCD) of two fractions is the least common multiple (LCM) of their denominators
simplified fraction
A fraction is considered simplified if there are no common factors in the numerator and denominator
complex fraction
A complex fraction is a fraction in which the numerator or the denominator contains a fraction

Chapter 5

Decimals

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Summary

Name the “number” part to the right of the decimal point as if it were a whole number Name the decimal place of the last digit Look for the word “and”—it locates the decimal point.

Key terms

mean
The mean of a set of n numbers is the arithmetic average of the numbers. The formula is mean = sum of values in data set n
median
The median of a set of data values is the middle value. Half the data values are less than or equal to the median. Half the data values are greater than or equal to the median
ratio
A ratio compares two numbers or two quantities that are measured with the same unit. The ratio of a to b is written a to b , a b , or a : b
diameter of a circle
A diameter of a circle is a line segment that passes through a circle’s center connecting two points on the circle
repeating decimal
A repeating decimal is a decimal in which the last digit or group of digits repeats endlessly
rate
A rate compares two quantities of different units. A rate is usually written as a fraction
radius of a circle
A radius of a circle is a line segment from the center to any point on the circle
equivalent decimals
Two decimals are equivalent decimals if they convert to equivalent fractions

Chapter 6

Percents

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Summary

Find the percent increase as a percent of the original amount If the denominator of the fraction is not 100, rewrite it as an equivalent fraction with denominator 100 Convert the fraction to a decimal by dividing the numerator by the denominator Write a sentence that gives the information to find it

Key terms

percent
A perfecnt is a ratio whose denominator is 100
percent increase
The percent increase is the percent the amount of increase is of the original amount
proportion
A proportion is an equation of the form a b = c d , where b ≠ 0 , d ≠ 0 .The proportion states two ratios or rates are equal. The proportion is read “ a is to b , as c is to d ”
simple interest
If an amount of money, P , the principal, is invested for a period of t years at an annual interest rate r , the amount of interest, I , earned is I = P r t . Interest earned…
discount
An amount of discount is a percent off the original price, determined by the discount rate
mark-up
The mark-up is the amount added to the wholesale price, determined by the mark-up rate
percent decrease
The percent decrease is the percent the amount of decrease is of the original amount

Chapter 7

The Properties of Real Numbers

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Summary

Identity Properties Identity Property of Addition: For any real number a : a + 0 = a 0 + a = a 0 is the additive identity Identity Property of Multiplication: For any real number a : a ⋅ 1 = a 1 ⋅ a = a 1 is the multiplicative identity Inverse Properties Inverse Property of Addition: For any real number a : a + ( - a ) = 0 - a is the additive inverse of a Commutative Properties Commutative Property of Addition: If a , b are real numbers, then a + b = b + a

Key terms

Real number
a real number is a number that is either rational or irrational
Multiplicative Identity
The multiplicative identity is 1. When one multiplies any number, it does not change the value
Additive Identity
The additive identity is 0. When zero is added to any number, it does not change the value
Additive Inverse
The opposite of a number is its additive inverse . The additive inverse of a is - a
Irrational number
An irrational number is a number that cannot be written as the ratio of two integers. Its decimal form does not stop and does not repeat
Rational number
A rational number is a number that can be written in the form p q , where p and q are integers and q ≠ 0 . Its decimal form stops or repeats
Multiplicative Inverse
The reciprocal of a number is its multiplicative inverse . The multiplicative inverse of a is 1 a

Chapter 8

Solving Linear Equations

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Summary

Simplify the expressions on both sides of the equation Determine whether the resulting equation is true Subtraction and Addition Properties of Equality Subtraction Property of Equality For all real numbers a, b, and c , if a = b then a - c = b - c Addition Property of Equality For all real numbers a, b, and c , if a = b then a + c = b + c

Key terms

solution of an equation
A solution of an equation is a value of a variable that makes a true statement when substituted into the equation

Chapter 9

Math Models and Geometry

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Summary

Make sure you understand all the words and ideas. You may need to read the problem two or more times. If there are words you don't understand, look them up in a dictionary or on the internet Choose a variable to represent that quantity

Key terms

irregular figure
An irregular figure is a figure that is not a standard geometric shape. Its area cannot be calculated using any of the standard area formulas
trapezoid
A trapezoid is four-sided figure, a quadrilateral, with two sides that are parallel and two sides that are not
similar figures
In geometry, if two figures have exactly the same shape but different sizes, we say they are similar figures
angle
An angle is formed by two rays that share a common endpoint. Each ray is called a side of the angle
cylinder
A cylinder is a solid figure with two parallel circles of the same size at the top and bottom
supplementary angles
If the sum of the measures of two angles is 180° , then they are called supplementary angles
complementary angles
If the sum of the measures of two angles is 90° , then they are called complementary angles
vertex of an angle
When two rays meet to form an angle, the common endpoint is called the vertex of the angle

Chapter 10

Polynomials

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Summary

Multiplying a Trinomial by a Binomial: To multiply a trinomial by a binomial, use the: Distributive Property Use the FOIL method for multiplying two binomials. Multiplying Two Binomials: To multiply binomials, use the: Distributive Property Exponential Notation This is read a to the m th power

Key terms

polynomial
A polynomial is a monomial, or two or more monomials, combined by addition or subtraction
trinomial
A trinomial is a polynomial with exactly three terms
binomial
A binomial is a polynomial with exactly two terms
greatest common factor
The greatest common factor (GCF) of two or more expressions is the largest expression that is a factor of all the expressions
scientific notation
A number expressed in scientific notation when it is of the form a × 10 n , where a ≥ 1 and a < 10 , and n is an integer
monomial
A term of the form a x m , where a is a constant and m is a whole number, is called a monomial
zero exponent
If a is a non-zero number, then a 0 = 1 . Any nonzero number raised to the zero power is 1
degree of a term
The degree of a term of a polynomial is the exponent of its variable

Chapter 11

Graphs

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Summary

Sign Patterns of the Quadrants Quadrant I Quadrant II Quadrant III Quadrant IV ( x , y ) (+,+) (-,+) (-,-) (+,-) Coordinates of Zero Points with a y- coordinate equal to 0 are on the x- axis, and have coordinates ( a , 0) Points with a x- coordinate equal to 0 are on the y- axis, and have coordinates ( 0, b )

Key terms

origin
The point ( 0 , 0 ) is called the origin. It is the point where the x -axis and y -axis intersect
quadrants
The x -axis and y -axis divide a rectangular coordinate system into four areas, called quadrants
y- coordinate equal to 0
on the x- axis, and have coordinates ( a , 0)
x- coordinate equal to 0
on the y- axis, and have coordinates ( 0, b )
horizontal line
A horizontal line is the graph of an equation that can be written in the form y = b . The line passes through the y- axis at ( 0 , b )
ordered pair
An ordered pair ( x , y ) gives the coordinates of a point in a rectangular coordinate system. The first number is the x -coordinate. The second number is the y -coordinate. ( x…
vertical line
A vertical line is the graph of an equation that can be written in the form x = a . The line passes through the x- axis at ( a , 0 )

Summaries and key terms on this page are taken from that chapter’s material already kept for this desk. They follow the OpenStax book. Margins is not affiliated with OpenStax. Resources, policy, and site safety