Tips And Tricks And Shortcut For Logarithm

Tips Tricks and Shortcuts Of Logarithms

Logarithm is the way to represent exponential expression as shown in the example .

Example : a x = y is a exponential expression And it can also be written as x = log a y . which is a logarithm expression.

Tips Tricks and Shortcuts Of Logarithms

Tips and Tricks and Shortcuts to solve Logarithm

  • The first question which arises in our mind is What is Logarithm?
  • Definition : The logarithm is the inverse function of exponentiation.
  • logarithm is a power to which a number must be raised to get another number.
  • Logarithm was introduced by John Napier in the early 17th century to simplify calculations.
  • A logarithm is of two types:-
    • Common Logarithm
    • Natural Logarithm
  • Common Logarithm- Logarithm with base 10 is Common logarithm.
  • Natural Logarithm-  Logarithm with base e is Natural Logarithm.
  • Example of Logarithm : log 100 = 2.

Taking LHS

log 102

= 2 log 10

= 2 × 1     (∴ Log 10 = 1 )

= 2 .

 

  • Let’s have a look on some question that will help better in understanding Logarithm.

Logarithm Tips and Tricks and shortcuts

Question 1 Which of the following statement is not correct?

Option

A) log (1 + 2 + 3) = log 1 + log 2 + log 3

B) log( 2+3) = log (2×3)

C) log10 1 = 0

D) log10 10 = 1

Solution:    a)  log( 1+2+3) = log6 = log (1×2×3) = log1+ log2+log3

b) log (2 + 3) = log 5 and log (2 x 3) = log 6 = log 2 + log 3

log (2 + 3) ≠ log (2 x 3)

c) Since,  loga 1=0,

so log10 1=0

d) Since, loga a = 1

so, log10 10 = 1.

Correct Answer : B

Question 2 If X is an integer then solve(log2 X)2– log2x4-32 = 0

Option

A) 256

B) 125

C) 375

d) None of these

Solution :    Let us consider,(log2 X)2– log2x4-32 = 0 —— equation 1

let log2 x= y

equation 1 = y2– 4y-32=0

y2-8y+ 4y – 32= 0

y(y-8) + 4(y-8) =0

(y-8) (y+4)= 0

y=8, y= -4

log2X=8 or, log2X = -4

X= 28 = 256, 0r 2-4 = \frac{1}{16} \

Since, X is an integer so X = 256.

Correct Answer : A

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