If the square of twice a number is 9 more than thrice the square of the given number, then the number can be .
A
3 or -3
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B
4 or -4
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C
5 or -5
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D
6 or -6
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Solution
The correct option is A 3 or -3 Let the number be x. Square of twice the number=(2x)2=4x2 Three times the square of the number=3x2 Given, square of twice the number is 9 more than three times the square of the number. ⇒4x2=3x2+9 ⇒x2−9=0 ⇒x2=9 ⇒x=±3