Twice squared

If the square of twice a number is 81, what is the number? Give a positive number x.

Correct answer:

x =  4.5

Step-by-step explanation:

(2x)2 = 81 2x = 81 = 9 9 = 9  x=9/2=29=421=4.5   Verifying Solution:  a=(2 x)2=(2 4.5)2=81



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