Think And Discuss

Prove the quotient rule using am/an = am+n.

(iii)   The Power Rule

When an exponential expression is raised to a power, we multiply the exponents i.e;(am)n = am.n

This property suggests the power rule.

Theorem: (Power Rule) Let a and x be positive real numebrs with a is not equal to 0 and n be any real number

then , logaXn = nlogax

i.e. the logarithm of a number with an exponent is the product of the exponent and the logerithm of that number

Try This

We have log2 3 = 5. Show that we get the same result by writing 32 = 52 and then using power rules. Verify the answer

Can we find the value of x such that 2x = 35?In such cases we find the value of 35 = 243.Then we can evaluate the value of x, for which the value of 2xequals to 243.

Applying the logarithm and using the formula logaxn = nlogax,Easily we can find the values of 325,333etc..

2x = 35

writing in logarthmic form

log235 = x

5 log23 = x  (Therefore ; logaxn = nlogax)

We observe that the value of x is the product of 5 and the value of log2 3.

Do This

Using logaxn = nlogax , expand the following

(i)log2725 (ii)log2850(iii) log523 (iv)log1024
Note : logx = log10x

Click here to know about "Power Rule"

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