Ncert Solutions for Class 8 Maths Chapter 12:Exponents CBSE Part 1

Evaluate
i) 3 ^-2
ii) (- 4) ^{- 2}
iii) (1/2)^-5  
Answer
As we know that
b^-n= 1/bⁿ
(i)  3^-2  =  1/ 3²  =1/9
(ii) (-4)^-2   =1/(-4)²= 1/6
(iii) (1/2)^-5   =1/ 2^-5 =2⁵= 32
Question 2
 Simplify and express the result in power notation with positive exponent.


Answer
(i)
= (-4)⁵ / (-4)⁸
= (-4)^5-8
=1/ (-4)³ (ii)

=   1/2^3x2
=1/2⁶

iv )

=   (3^-7/ 3^-10) × 3^-5
=3^-7+10 × 3^-5
=3³ × 3^-5
=3^-2
=1/3²
v) 2 ^{- 3} × ( - 7) ^{- 3}
=   (2× -7)^-3
= (-14)^-3
=1/ (-14)³
Question 3
Find the value of

1. (3⁰ + 4 ^{- 1}) × 2²
2. (2 ^{- 1} × 4 ^{- 1})  ÷ 2 ^{- 2}
3. 
   
4. (3 ^{- 1} + 4 ^{- 1} + 5 ^{- 1})⁰
5. 
   Answer
   

1. (3⁰ + 4 ^{- 1}) × 2² = (1+1/4) × 4
   = 4+1=5
   

     2. (2 ^{- 1} × 4 ^{- 1})  ÷ 2 ^{- 2}
= [(1/2) × (1/4)] ÷ (1/4)
= (1/8)  ×  (4)  =1/2
  3.

= 2² + 3²  + 4²
=4+9+16=29
4. (3 ^{- 1} + 4 ^{- 1} + 5 ^{- 1})⁰
=1   as  a⁰=1

Question 4
Evaluate

Answer


Question 5
Find the value of m for which 5^m   ÷  5^-3 = 5⁵

Answer
5^m   ÷   5^-3 = 5⁵
5^m × (1/5^-3)  = 5⁵
5^m+3 =5⁵
So  m+3=5
m=2
Question 6
Evaluate

Answer

Question 7
Simplify.


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Class 8 Maths Class 8 Science