Question

For what value of k the equation 9 x2 + 60k x + 4 =0 has equal roots.​

Answer 1

Answer:

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Answer 2

Answer:

k = 1/ 5

Step-by-step explanation:

Given equation :-

9 x² + 60k x + 4 = 0 .   .   .   .    . (i)

The equation has equal roots.

[roots of an equation are such values that satisfies the condition of that particular equation]

For an equation to have equal roots its discriminant (D) must be equal to 0.

For an equation, ax² + bx + c = 0 .   .   .   .  (ii)

it's D = b² - 4ac

On comparing eqn (i) and (ii) :

• a = 9
• b = 60k
• c = 4

Calculating D for the eqn (i) :-

=> D = b² - 4ac

= (60k)² - (4 × 9 × 4)

D = 3600k² - 144

Since, the equation has equal roots, it's D = 0

=> 3600k² - 144 = 0

=> 3600k² = 144

=> k² = 144/ 3600

=> k² = 1/ 25

=> k =1/ 5