Question

Find the value of k for which the roots of `9x^2+8kx+16=0` are real and equal 

 

Answer 1

Given: 

`9x^2+8kx+16=0` 

Here,  

`a=9, b=8k, and c=16` 

It is given that the roots of the equation are real and equal; therefore, we have: 

`D=0` 

⇒`(b^2-4ac)=0` 

⇒`(8k)^2-4xx9xx16=0` 

⇒`64k^2-576=0` 

⇒`64k^=576` 

⇒`k^2=9`  

⇒`k=+-3` 

∴ `k=3 or k=-3`