Question

IF the quadratic equation 2x2-kx+9 = 0 has equal roots, then the value of k is
(A) -6under root 2 only
(B) 6 only
(C) 6under root 2 only
(D) +-6 under root 2

Answer 1

Answer:

i know ur aakashian and its OT-2

Step-by-step explanation:

Answer 2

Answer:

The correct answer is option (D)±6√2

Step-by-step explanation:

Given,

The quadratic equation  2x²-kx+9 = 0 has equal roots.

To find

The value of k

Recall the concept

The discriminant of a quadratic equation of the form ax² + bx + c = 0 is given by  b² - 4ac

The quadratic equation has equal roots b² - 4ac = 0

Solution:

Given equation is 2x²-kx+9 = 0. Comparing this equation with ax² + bx + c = 0, we get

a = 2, b = -k and c = 9

Since the roots of the equation 2x²-kx+9 = 0 are equal we have

b² - 4ac = 0

(-k)² - 4×2×9 = 0

k² - 72 = 0

k² =  72

k = ±$\sqrt{72}$

=  ±$\sqrt{9X4X2}$

= ±6√2

∴ The value of k = ±6√2

The correct answer is option (D)±6√2

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