Q. Which is equal to 8421?Choices:(A) (−84)2(B) −842(C) 84−2(D) 84−21
Understand Expression: Understand the given expression 8421. The given expression is a fraction where the numerator is 1 and the denominator is 84 raised to the power of 2. This is a positive exponent, so the base 84 is being squared in the denominator.
Apply Negative Exponent Rule: Apply the negative exponent rule to find an equivalent expression.The negative exponent rule states that a−m=am1. Therefore, if we want to express 8421 with a negative exponent, we would write it as 84−2.
Compare with Choices: Compare the given choices with the equivalent expression 84−2. (A) (−84)2 is not equivalent because it represents a positive square of −84, not a fraction. (B) −842 is not equivalent because it represents the negative of 84 squared, not a fraction. (C) 84−2 is equivalent because it represents 1/842 using the negative exponent rule. (D) 1/84−2 is not equivalent because it would represent 1/(1/842), which simplifies to 842, not 1/842.