McGraw Hill Glencoe Algebra 1, 2012
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McGraw Hill Glencoe Algebra 1, 2012 View details
2. Real Numbers
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Exercise 3 Page p10

Can you simplify the number?

Irrational number

Before we consider the given number, let's recall the various types of numbers.

  • Rational Number: A number is a rational number if it can be written in the form ab, where a and b are both integers and b≠ 0.
  • Integer: A number is an integer if it is a positive or negative counting number (or zero). All integers are also rational numbers because any number can be written as a division by one, a1.
  • Whole Number: A number is a whole number if it is a non-negative counting number. All whole numbers are also integers and rational numbers.
    • Natural Number: A number is a natural number if it is a positive counting number. All natural numbers are also whole numbers, integers, and rational numbers.
    • Irrational Number: An irrational number is a number that cannot be written in the form of a rational number. These are recognized as being non-repeating, infinite decimals.

    Now, let's try to categorize the given number using these definitions. sqrt(28) Let's simplify this square root as much as possible.

    sqrt(28)
    sqrt(4*7)
    sqrt(4)*sqrt(7)
    sqrt(2*2)*sqrt(7)
    sqrt(2^2)*sqrt(7)
    2*sqrt(7)

    We can use a calculator to find the exact value of the remaining square root part. sqrt(7)=2.6457513... Because the decimal part is infinite with non-repeating digits, sqrt(7) is an irrational number. Furthermore, any irrational number multiplied by a non-zero number will remain an irrational number. Therefore, sqrt(28) is an irrational number.