A number is multipled by its double and the answer is 72. What is the number ?

asked Jul 4, 2019 188k views

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$x * 2x = 72 \\ 2x^(2) = 72 \\ (2x^(2) )/(2) = (72)/(2) \\ {x}^(2) = 36 \\ \sqrt{ {x}^(2) } = 36 \\ x = 6$

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3 votes

Let x be the number

Then,
x(2x) = 72
2x^2 = 72
x^2 = 36
x = ±√36
x = ±6

The number could be 6 and -6.

Leonidos answered Jul 9, 2019

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