The Fraction Raised to a Negative Exponent Rule

When you have a fraction raised to a negative exponent, you can simply replace it with the reciprocal of the fraction raised to a positive exponent.

[tex] \left(\frac{a}{b}\right)^{-n}=\left(\frac{b}{a}\right)^n [/tex]

Simplify the following:

[tex] \left(\frac{2}{5}\right)^{-2} = \square [/tex]

Simplify:

[tex] \left(\frac{x^3}{7}\right)^{-3} = \square [/tex]



Answer :

Certainly! Let's simplify the given expressions step-by-step using the reciprocal rule for negative exponents.

Expression 1:
[tex]\[ \left(\frac{2}{5}\right)^{-2} \][/tex]

Step 1: Apply the reciprocal rule, which states that [tex]\(\left(\frac{a}{b}\right)^{-n} = \left(\frac{b}{a}\right)^n\)[/tex].

[tex]\[ \left(\frac{2}{5}\right)^{-2} = \left(\frac{5}{2}\right)^2 \][/tex]

Step 2: Raise the fraction [tex]\(\left(\frac{5}{2}\right)\)[/tex] to the power of [tex]\(2\)[/tex].

[tex]\[ \left(\frac{5}{2}\right)^2 = \frac{5^2}{2^2} = \frac{25}{4} = 6.25 \][/tex]

So, the simplified form of [tex]\(\left(\frac{2}{5}\right)^{-2}\)[/tex] is:

[tex]\[ 6.25 \][/tex]

Expression 2:
[tex]\[ \left(\frac{x^3}{7}\right)^{-3} \][/tex]

Step 1: Apply the reciprocal rule, which states that [tex]\(\left(\frac{a}{b}\right)^{-n} = \left(\frac{b}{a}\right)^n\)[/tex].

[tex]\[ \left(\frac{x^3}{7}\right)^{-3} = \left(\frac{7}{x^3}\right)^3 \][/tex]

Step 2: Raise the fraction [tex]\(\left(\frac{7}{x^3}\right)\)[/tex] to the power of [tex]\(3\)[/tex].

[tex]\[ \left(\frac{7}{x^3}\right)^3 = \frac{7^3}{(x^3)^3} = \frac{343}{x^9} \][/tex]

So, the simplified form of [tex]\(\left(\frac{x^3}{7}\right)^{-3}\)[/tex] is:

[tex]\[ \frac{343}{x^9} \][/tex]

Thus, the final simplified answers are:

[tex]\[ \left(\frac{2}{5}\right)^{-2} = 6.25 \][/tex]
[tex]\[ \left(\frac{x^3}{7}\right)^{-3} = \frac{343}{x^9} \][/tex]