Question

87. (21) ? X (21) 6.5 = (21) 12.4
a. 18.9
b, 6.9
c. 4.4
d. इनमें से कोई नहीं


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Answer 1

Answer:

b is the correct answer please mark me brainlest please

Answer 2

Given :

(21) ? X (21) 6.5 = (21) 12.4

To find :

The correct option from the following options

Solution:

As we know that

$21^{?}*21^{6.5} =21^{12.4}$

Let us assume

? = x so we get

$21^{x}*21^{6.5} =21^{12.4} \\21^{x + 6.5} =21^{12.4}$by comparing their bases

Base are same in both the sides

So the exponent should be same.

$x + 6.5=12.4\\x=12.4-6.5\\x=5.9$

Hence, the correct option (b) will be correct which is 5.9 not 6.9.