Which shows how to find the value of this expression when [tex] x=-2 [/tex] and [tex] y=5 [/tex]?

[tex] \left(3 x^3 y^{-2}\right)^2 [/tex]

A. [tex] \frac{3^2(-2)^6}{5^4} [/tex]

B. [tex] \frac{3(-2)^6}{5^4} [/tex]

C. [tex] \frac{3^2(5)^6}{(-2)^4} [/tex]

D. [tex] \frac{3}{(2)^6 5^4} [/tex]



Answer :

Certainly! Let's go through the solution of the given expression step by step:

We have the expression:

[tex]\[ \left(3 x^3 y^{-2}\right)^2 \][/tex]

where [tex]\( x = -2 \)[/tex] and [tex]\( y = 5 \)[/tex].

### Step-by-Step Solution:

1. Calculate [tex]\( x^3 \)[/tex] and [tex]\( y^{-2} \)[/tex]:
- [tex]\( x = -2 \)[/tex], so [tex]\( x^3 = (-2)^3 = -8 \)[/tex].
- [tex]\( y = 5 \)[/tex], so [tex]\( y^{-2} = \frac{1}{y^2} = \frac{1}{5^2} = \frac{1}{25} = 0.04 \)[/tex].

2. Combine the expression [tex]\( 3 x^3 y^{-2} \)[/tex]:
- First, calculate [tex]\( 3 x^3 \)[/tex]:
[tex]\[ 3 x^3 = 3 \cdot (-8) = -24 \][/tex]

- Now, multiply by [tex]\( y^{-2} \)[/tex]:
[tex]\[ 3 x^3 y^{-2} = -24 \cdot 0.04 = -0.96 \][/tex]

3. Square the combined result:
- We now have:
[tex]\[ \left(-0.96\right)^2 = 0.9216 \][/tex]

So the simplified value of the expression when [tex]\( x = -2 \)[/tex] and [tex]\( y = 5 \)[/tex] is [tex]\( 0.9216 \)[/tex].

### Evaluating Given Options:

Let's check the given options with our calculated values:

1. [tex]\(\frac{3^2(-2)^6}{5^4}\)[/tex]
- Calculate:
[tex]\[ (3^2 = 9), \; (-2)^6 = 64, \; (5^4 = 625) \][/tex]
- Hence:
[tex]\[ \frac{9 \cdot 64}{625} = \frac{576}{625} = 0.9216 \][/tex]
- This matches our calculated value of [tex]\( 0.9216 \)[/tex].

2. [tex]\(\frac{3(-2)^6}{5^4}\)[/tex]
- Calculate:
[tex]\[ 3 \cdot 64 = 192 \][/tex]
- Hence:
[tex]\[ \frac{192}{625} \][/tex]
- This does not match our calculated value.

3. [tex]\(\frac{3^2(5)^6}{(-2)^4}\)[/tex]
- This option's calculation is quite different from what we need, and evaluating would give a completely different number.

4. [tex]\(\frac{3}{(2)^6 5^4}\)[/tex]
- Calculate:
[tex]\[ 2^6 = 64 \][/tex]
[tex]\[ 3 / (64 \cdot 625) \][/tex]
- This fraction would be much smaller than our calculated value.

Conclusion:

The correct option that matches our calculated value is:

[tex]\(\frac{3^2(-2)^6}{5^4}\)[/tex]

So, the correct option is the first one.