Question

If the roots of the equation 12x² + mx + 5 = 0 are real and equal then m is equal to 

A) 4 \(\sqrt{15}\)

B) 2 \(\sqrt{15}\)

C) 8 \(\sqrt{15}\)

D) 10√5

Answer 1

Correct option is (A) \(4\sqrt{15}\)

Given that roots of the equation \(12x^2+mx+5=0\) are real and equal.

\(\therefore m^2-4\times12\times5=0\)

\(\Rightarrow m^2=240\)

\(\Rightarrow m^2=16\times15\)

\(\Rightarrow m=\pm\sqrt{16\times15}\)

\(=\pm4\sqrt{15}\)

Answer 2

Correct option is A) 4 \(\sqrt{15}\)