Joe is correct as the unknown number is 6.
The exponents of a number are defined as the representation of a number that shows how many times a number is multiplied by itself.
Given :
[tex](x^2)^?=x^4\times x^8[/tex]
Let the question mark exponent outside the bracket be y, which needs to be determined
[tex](x^2)^y=x^4\times x^8[/tex]
Simplify the equation by applying exponent rules to either side of the equation:
Apply the rule [tex](a^b)^c = a^{b \times c}[/tex]
[tex](x^2)^y=x^4\times x^8[/tex]
[tex](x)^{2y}=x^4\times x^8[/tex]
Now apply [tex]a^b \times a^c = a^{b+c}[/tex]
[tex](x)^{2y}=x^{4+8}\\\\(x)^{2y}=x^{12}[/tex]
So, the base is the same the exponent will be the same also,
2y = 12
y = 6
Hence, Joe is correct as the unknown number is 6.
Learn more about exponentiation here:
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