An unknown variable ..............
Answer:

Step-by-step explanation:


Sorry but i only know the answer to number 3
<span>
A rational number is a number that can be written as a fraction where numerator and denominator are both integers (and the denominator is not zero).
Since 0.57 = 57/100, so the number 0.57 can be written as a fraction where the numerator (57) and denominator (100) are both integers. </span>
Answer: Choice (3): 

Remember that negative power is the same as reciprocal if the same magnitude power but positive.
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