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Question : Five times of a positive integer is equal to 3 less than twice the square of that number. The number is:

Option 1: 3

Option 2: 13

Option 3: 23

Option 4: 33


Team Careers360 6th Jan, 2024
Answer (1)
Team Careers360 13th Jan, 2024

Correct Answer: 3


Solution : Let the positive integer be $x$.
$5x+3 = 2x^{2}$
⇒ $2x^{2}- 5x-3=0$
⇒ $2x^{2}- 6x+x-3=0$
⇒ $2x(x-3)+1(x-3)=0$
⇒ $(2x+1)(x-3)=0$
Since $x$ cannot be negative,
⇒ $(x-3)=0$
⇒ $x=3$
Hence, the correct answer is 3.

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