Question

find the value of k for which x equal to 2 is a zero of the quadratic polynomial 3 x square minus kx minus2=0​

Answer 1

Answer:

• k = 5

Explanation:

Let the given polynomial,

⇒ p(x) = 3x² - kx - 2

Whose one of the zeros is x = 2

We need to find the value of k.

On substituting the value of x in p(x)

⇒ 3x² - kx - 2 = 0

⇒ 3(2)² - k(2) - 2 = 0

⇒ 3(4) - 2k - 2 = 0

⇒ 12 - 2k - 2 = 0

⇒ 10 - 2k = 0

⇒ -2k = -10

⇒ 2k = 10

⇒ k = 10/2

⇒ k = 5

∴ The value of ‘k’ is 5

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Verification :

Let's substitute the value of x and k in p(x)

⇒ 3x² - kx - 2 = 0

⇒ 3(2)² - k(2) - 2 = 0

⇒ 3(4) - 2k - 2 = 0

⇒ 12 - 2k - 2 = 0

⇒ 10 - 2k = 0

⇒ 10 - 2(5) = 0

⇒ 10 - 10 = 0

⇒ 0 = 0

Since, L. H. S. = R. H. S.

Hence, verified !