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3) Which of the following is NOT equal to 4?

A. [tex] (1)^{-2} \times 2^2 [/tex]
B. [tex] (-2)^2 [/tex]
C. [tex] 2^{-2} [/tex]
D. [tex] 2 \times 2^1 [/tex]

4)

A. 121.5 ml
B. 124 ml
C. 125 ml
D. 128 ml


Sagot :

To determine which of the given options is NOT equal to 4, let's evaluate each expression step-by-step:

### Option A: [tex]\( (1)^{-2} \times 2^2 \)[/tex]

1. Calculate [tex]\( (1)^{-2} \)[/tex].
- Any number raised to the power of 0 is 1.
- Therefore, [tex]\( (1)^{-2} = 1^ {-2}= 1 \)[/tex].

2. Calculate [tex]\( 2^2 \)[/tex].
- [tex]\( 2^2 = 4 \)[/tex].

3. Multiply the results from steps 1 and 2.
- [tex]\( 1 \times 4 = 4 \)[/tex].

So, [tex]\( (1)^{-2} \times 2^2 = 4 \)[/tex].

### Option B: [tex]\( (-2)^2 \)[/tex]

1. Calculate [tex]\( (-2)^2 \)[/tex].
- When a negative number is squared, the result is positive.
- [tex]\( (-2)^2 = (-2) \times (-2) = 4 \)[/tex].

So, [tex]\( (-2)^2 = 4 \)[/tex].

### Option C: [tex]\( 2^{-2} \)[/tex]

1. Calculate [tex]\( 2^{-2} \)[/tex].
- [tex]\( 2^{-2} = \frac{1}{2^2} \)[/tex].
- [tex]\( 2^2 = 4 \)[/tex].
- Therefore, [tex]\( 2^{-2} = \frac{1}{4} = 0.25 \)[/tex].

So, [tex]\( 2^{-2} = 0.25 \)[/tex], which is NOT equal to 4.

### Option D: [tex]\( 2 \times 2^1 \)[/tex]

1. Calculate [tex]\( 2^1 \)[/tex].
- [tex]\( 2^1 = 2 \)[/tex].

2. Multiply the results from step 1 by 2.
- [tex]\( 2 \times 2 = 4 \)[/tex].

So, [tex]\( 2 \times 2^1 = 4 \)[/tex].

### Conclusion

From the above evaluations, we can see that Option C, [tex]\( 2^{-2} \)[/tex], equals [tex]\( 0.25 \)[/tex], which is NOT equal to 4. Therefore, the correct answer is:

[tex]\[ \boxed{C} \][/tex]