Question

The value of k for which the equation 9x2 +8kx+8=0 has equal roots

Answer 1

Step-by-step explanation:

b^2-4ac

(8k)^2-4(9)(8)=0

64k^2-288=0

64k^2=288

k^2= 288/64

k^2=9/2

k= 3/√2

or 3/1.414=2.1213

Answer 2

Step-by-step explanation:

When rooots are equal, determinant is equal to zero.

D= 0

=> b^2 - 4ac= 0

=> (8k)^2- 4×9×8= 0

=> 64k^2 - 288=0

=> 64k^2=288

=> 2k^2= 9

=> k= 3/root 2

=> k= 3×root2/2