Big Ideas Math: Modeling Real Life, Grade 8
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Big Ideas Math: Modeling Real Life, Grade 8 View details
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Exercise 14 Page 418

Think of a number that is - 827 when it is multiplied by itself three times.

- 2/3

Practice makes perfect
The cube root of a number a is another number b if b multiplied by itself three times is a. This means that if b is the cube root of a, then b raised to the third power results in a. Let's see some examples of this. sqrt(a)= b because b^3= a [0.8em] c|c sqrt(- 8)= - 2 & sqrt(27)= 3 because( - 2)^3= - 8 & because 3^3= 27 We will now find the cube root of - 827. We need to think of a number that is - 827 when it is multiplied by itself three times. ?^3= - 827 We see that - 23 raised to the third power is - 827, so the number we are looking for is - 23.
(- 2/3)(- 2/3)(- 2/3)
(-2/3)(-2/3)(-2/3)
(-2)(-2)(-2)/3*3*3
(- 2)^3/3^3
- 8/27
- 8/27
This means that the cube root of - 827 is - 23. sqrt(- 827) = - 23