Question

6. Find the value of 'k' for which 9x2 + 3kx + 4 = 0 has real and equal roots.​

Answer 1

$\huge\bf\color{navy}{Question~:-}$

Find the value of ‛k’ for which $\bf{9x^{2}+3kx+4}$ has real and equal roots.

$\huge\bf\color{navy}{Answer~:-}$

$\bf{Given~the~equation~has~equal~roots~;}$

$\bf{~~~~~~~~~~b^{2}-4ac=0}$

$\implies\bf{(3k)^{2}-4(9)(4)=0}$

$\implies\bf{9k^{2}-4(36)=0}$

$\implies\bf{9k^{2}-144=0}$

$\implies\bf{9k^{2}=144}$

$\implies\bf{k^{2}={\frac{144}{9}}=16}$

$\implies\bf{k={\sqrt{16}}}$

$\bf{~~~~~\therefore~k={\underline{\underline{±4}}}}$

$\huge\bf\color{navy}{Hope~it~helps..!!}$