Question

Find the values of k for which the given quadratic equation has real and distinct roots: 

`9x^2+3kx+4=0` 

 

 

Answer 1

The given equation is `9x^2+3kx+4=0` 

∴`D=(3k)^2-4xx9xx4=9k^2-144` 

The given equation has real and distinct roots if` D>0` 

∴`9k^2-144>0` 

⇒`9(k^2-16)>0` 

⇒`(k-4)(k+4)>0` 

⇒`k<-4  or  k>4`