Question

4. Find the value of k so that the quadratic
equation 9x^2- 3kx = has equal roots
​

Answer 1

Answer:

Step-by-step expk = 4

Step-by-step explanation:

Our given equation is :

9 x² - 3 k x + k = 0

Comparing with a x² + b x + c = 0 we get :

a = 9

b = - 3  k

c = k .

Whenever we are told that the equation has equal roots then :

b² = 4 a c

This method can be used effectively to calculate the value of k .

( - 3 k )² = 4 ( 9 ) ( k )

⇒ 9 k² = 36 k

⇒ k² = 36 k / 9

⇒ k² = 4 k

⇒ k = 4

The value of k is 4 .

NOTE :

If the equation had real and unequal roots , then :

b² > 4 ac

If the equation had imaginary roots then :

b² < 4 aclanation: