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Which is the value of this expression when a = 5 and k = negative 2?

(StartFraction 3 squared a Superscript negative 2 Baseline Over 3 a Superscript negative 1 Baseline EndFraction) Superscript k
StartFraction 1 Over 75 EndFraction
StartFraction 9 Over 25 EndFraction
StartFraction 25 Over 9 EndFraction
75

Respuesta :

Answer:

StartFraction 25 Over 9 EndFraction

Step-by-step explanation:

[tex] \bigg( \huge{\frac{ {3}^{2}a ^{ - 2} }{3 {a}^{ - 1} }} \bigg)^{k} \\ \\ = \bigg( \huge{\frac{ 9a }{3 {a}^{ 2} }} \bigg)^{k} \\ \\ = \bigg( \huge{\frac{ 3 }{ {a}}} \bigg)^{k} \\ \\ = \bigg( \huge{\frac{ 3 }{ {5}}} \bigg)^{ - 2} \\ \\ = \bigg( \huge{\frac{ 5 }{ {3}}} \bigg)^{ 2} \\ \\ = \huge{\frac{ 25 }{ {9}}} [/tex]

The value of the expression [tex](\frac{3^{2}a^{-2} }{3a^{-1} } )^{k}[/tex] when a = 5 and k = -2 is [tex]\frac{25}{9}[/tex].

What are the exponent rules?

Product of powers rule -Add powers together when multiplying like bases. That is

[tex]x^{m} .x^{n} = x^{m+n}[/tex]

Quotient of powers rule- Subtract powers when dividing like bases.

[tex]\frac{x^{m} }{x^{n} } =x^{m-n}[/tex]

Power of powers rule - Multiply powers together when raising a power by another exponent.

[tex](x^{m} )^{n} = x^{mn}[/tex]

What is substitution?

Substitution means putting numbers in place of letters to calculate the value of an expression .

According to the given question.

We have an expression.

[tex](\frac{3^{2}a^{-2} }{3a^{-1} } )^{k}[/tex]

The above expression can be written as

[tex](\frac{3^{2}a^{-2} }{3a^{-1} } )^{k}[/tex]

[tex]= (\frac{9a^{-2} }{3a^{-1} } )^{k}[/tex]

[tex]= (\frac{3a^{-2} }{a^{-1} } )^{k}[/tex]                 (cancelling 9 by 3)

[tex]=(3a^{-2+1} )^{k}[/tex]              (quotient of power rule)

[tex]=(3a^{-1} )^{k}[/tex]

Substitute a = 5 and  k = -2 in the above expression.

[tex]\implies (3(5)^{-1} )^{-2}[/tex]

[tex]\implies (3)^{-2} 5^{-1(-2)}[/tex]                    (power of powers rule)

[tex]\implies \frac{(5)^{2} }{(3)^{2} }[/tex]

[tex]\implies \frac{25 }{9}[/tex]

Hence, the value of the expression [tex](\frac{3^{2}a^{-2} }{3a^{-1} } )^{k}[/tex] when a = 5 and k = -2 is [tex]\frac{25}{9}[/tex].

Find out more information about substitution and exponent rules here:

https://brainly.com/question/26629824

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