Adding 42 to a given positive number gives the same result as squaring the number. Find the number

A. 14

B. 13

C. 7

D. 6

Correct Answer: Option C

**C. 7**

Explanation

Let the given positive number be x

Then 4 + x = x²

0 = x² – x – 4²

or x² – x – 4² = 0

x² – 7x + 6x – 4² = 0

x(x – 7) + 6(x – 7) = 0

= (x + 6)(x – 7) = 0

x = -6 or x = 7

Hence, x = 7

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