Answer :
Final answer:
None of the choices (-7, 49, or 7) is equivalent to -49. Equivalence in mathematics means expressions have the same value, and none of the given options match the value of -49. So, the correct option is 'None of these'.
Explanation:
The question seems to be asking which of the given choices are equivalent to the expression -49. The options provided appear to be: a. -7, b. 49, c. 7id (which seems to be a typo and should be just 7), and d. 49. The correct choice that is equivalent to -49 is none of the options provided because neither -7, 49, nor 7 is equal to -49. If we are to find the square root of -49, it would be −7 (the negative square root of 49), but since that option is not given, we assume it is simply asking for an equivalent expression to -49.
It is also important to understand that in mathematics, an expression is equivalent to another if they have the same value. In this case, -49 is a specific numerical value, and none of the options provided match this value.
Considering the additional information provided, none of it seems directly relevant to this question about equivalence, as it pertains to different mathematical concepts such as scientific notation and vectors, which are not necessary for solving the query at hand.