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Find the value of (12)-2+(13)-2+(14)-2

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Question

Find the value of `(1/2)^(-2)+(1/3)^(-2)+(1/4)^(-2)`

Sum
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Solution

`(1/2)^(-2)+(1/3)^(-2)+(1/4)^(-2)`

= `(2/1)^(2)+(3/1)^(2)+(4/1)^(2)`     `(thereforea^(-m)=1/a^m)`

= 22 + 32 + 42

= 4 + 9 + 16

= 29

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Chapter 10: Exponents and Powers - EXERCISE 10.1 [Page 125]

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NCERT Mathematics [English] Class 8
Chapter 10 Exponents and Powers
EXERCISE 10.1 | Q 3. (iii) | Page 125

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RELATED QUESTIONS

Find the value of `{((-2)/3)^(-2)}^2`


Simplify:

\[\left( 3^2 - 2^2 \right) \times \left( \frac{2}{3} \right)^{- 3}\]

Simplify:
\[\left\{ 4^{- 1} \times 3^{- 1} \right\}^2\]


Express the following rational numbers with a positive exponent:

\[\left\{ \left( \frac{4}{3} \right)^{- 3} \right\}^{- 4}\]

By what number should \[\left( \frac{1}{2} \right)^{- 1}\] be multiplied so that the product may be equal to \[\left( \frac{- 4}{7} \right)^{- 1} ?\]


By what number should \[\left( \frac{5}{3} \right)^{- 2}\] be multiplied so that the product may be \[\left( \frac{7}{3} \right)^{- 1} ?\]


Which of the following numbers is not equal to \[\frac{- 8}{27}?\]
(a) \[\left( \frac{2}{3} \right)^{- 3}\]

(b) \[- \left( \frac{2}{3} \right)^3\]

(c) \[\left( - \frac{2}{3} \right)^3\]

(d) \[\left( \frac{- 2}{3} \right) \times \left( \frac{- 2}{3} \right) \times \left( \frac{- 2}{3} \right)\]


The expression for 4–3 as a power with the base 2 is 26.


Predicting the ones digit, copy and complete this table and answer the questions that follow.

 Powers Table
x 1x 2x 3x 4x 5x 6x 7x 8x 9x 10x
1 1 2                
2 1 4                
3 1 8                
4 1 16                
5 1 32                
6 1 64                
7 1 128                
8 1 256                
Ones
Digits
of the
Powers
1 2, 4, 8, 6                
  1. Describe patterns you see in the ones digits of the powers.
  2. Predict the ones digit in the following:
    1. 412
    2. 920
    3. 317
    4. 5100
    5. 10500
  3. Predict the ones digit in the following:
    1. 3110
    2. 1210
    3. 1721
    4. 2910 

Simplify and express the result in power notation with positive exponent.

2−3 × (−7)−3


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