Question

Which of the following is the value of k, if one root of the Quadratic equation +r-8 =0 is -4 ?​

Answer 1

Let m be the one root of given equation then the other root be 2m.

Then 3m=−

a

b

orm=−

3a

b

Now m(2m)=

a

c

(

3a

−b

)(

3a

−2b

)=

a

c

∴2b

2

=9ac