Q. If 2m=x and 7n=y, then which of the following is equivalent to 784mn ?Choose 1 answer:(A) x2m⋅y4n(B) x2n⋅y4m(C) x4m⋅y2n(D) x4n⋅y2m
Expressing 784 as Prime Factors: First, let's express 784 as a product of its prime factors.784=24×72This is because 784 is divisible by 2 four times (2×2×2×2=16) and by 7 twice (7×7=49), and 16×49=784.
Raising Prime Factorization to Power: Now, let's raise this prime factorization to the power of mn: (24×72)mn=(24mn)×(72mn)We distribute the exponent mn to both 24 and 72.
Substituting Variables: Next, we substitute x for 2m and y for 7n according to the given information:2m=x and 7n=ySo, 24mn becomes x4n and 72mn becomes y2m.
Writing the Expression with Substituted Variables: Now, we write the expression with the substituted variables:(24mn)×(72mn)=x4n×y2mThis matches one of the answer choices.
Comparing with Answer Choices: We compare our expression with the answer choices:(A) x2m⋅y4n(B) x2n⋅y4m(C) x4m⋅y2n(D) x4n⋅y2mOur expression is x4n⋅y2m, which matches answer choice (D).
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