Roots of quadratic equation $m^{2}\,-\,84\,=\,0$ is
- $+\,2\sqrt{21}$
- $-\,2\sqrt{21}$
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Both A and B
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None of these
Reveal answer
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C
Correct answer
Explanation
m^2 - 84 = 0 implies m^2 = 84. m = +/- sqrt(84) = +/- sqrt(4 * 21) = +/- 2 * sqrt(21).
AI explanation
To solve m squared minus 84 equals 0, isolate m squared by adding 84 to both sides to get m squared equals 84. Taking the square root of both sides yields m equals plus or minus the square root of 84. By factoring 84 into 4 times 21, we can simplify the radical to m equals plus or minus 2 times the square root of 21. This shows that both positive and negative 2 times the square root of 21 are the correct roots.