Post a New Question

math

posted by .

How can you tell if a number is rational or irrational?

a) 3.215 (there is a line drawn over the 15)
b.) square root 10
c) 0.143639854024
d)4.312

can you please explain what i need to look at to tell which is which?

  • math -

    any number whose decimal expression terminates or ends in a repeating group of digits is rational. Otherwise, probably not.

    (a) 3.21515151515...
    3 + 2/10 + 15/990 is rational

    To find out what .0151515... is, let it be x

    x = .015151515...
    10x = .151515
    1000x = 15.15151515...
    subtract 10x from 1000x:
    990x = 15
    x = 15/990

    (b)the square root of any number which is not a perfect square is irrational

    (c) If that's exact, it terminates and is rational
    (d) same

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math, ( Help please?)!

    Tell whether each number is a real number, rational number, irrational, interger, or whole number, and then order then from least to greatest. ( Square root sign) 49, 8, -( square root sign) 4, and -3. Could someone explain to me how …
  2. 7th grade math Ms.Sue please

    1. Which of these numbers can be classified as both real and irrational?
  3. Math ~CHECK MY ANSWER~

    1) Which of these is a rational number? a. Pi b. Square root 3 ****** c. Square root 2 d. 1.3 (the # 3 has a line at the top) 2) Which of the following sets contains 3 irrational numbers?
  4. math

    which number has the greatest value? a 3.5 b square root of 15** c square root of 1/16 d 26/100 which number is an irrational number?
  5. math

    1) Which of these is a rational number? a. Pi b. Square root 3 ****** c. Square root 2 d. 1.3 (the # 3 has a line at the top) 2) Which of the following sets contains 3 irrational numbers?
  6. math

    1. Which of the following numbers is a rational?
  7. Math

    1. Which of the following numbers is a rational?
  8. math

    1. Which of the following numbers is a rational?
  9. Math

    1. Which of the following numbers is a rational?
  10. Math

    1. Which of these numbers can be classified as both real and irrational?

More Similar Questions

Post a New Question