KnowledgeBoat Logo
|

Mathematics

Find the value of k, if x - 1 is a factor of p(x) in each of the following cases:

(i) p(x) = x2 + x + k

(ii) p(x) = 2x2 + kx + 2\sqrt{2}

(iii) p(x) = kx2 - 2\sqrt{2}x + 1

(iv) p(x) = kx2 - 3x + k

Polynomials

8 Likes

Answer

(i) p(x) = x2 + x + k

⇒ x - 1 = 0

⇒ x = 1

Putting x = 1 we get,

p(1) = (1)2 + 1 + k

= 1 + 1 + k

⇒ 2 + k = 0

⇒ k = -2

So the value of k = -2

(ii) p(x) = 2x2 + kx + 2\sqrt{2}

⇒ x - 1 = 0

⇒ x = 1

Putting x = 1 we get,

p(1) = 2(1)2 + k(1) + 2\sqrt{2}

⇒ 2 + k + 2\sqrt{2}

⇒ k = -2 -2\sqrt{2}

⇒ k = -(2 + 2\sqrt{2})

So the value of k = -(2 + 2\sqrt{2})

(iii) p(x) = kx2 - 2\sqrt{2}x + 1

⇒ x - 1 = 0

⇒ x = 1

Putting x = 1 we get,

p(1) = k(1)2 - 2\sqrt{2}(1) + 1

⇒ k - 2\sqrt{2} + 1 = 0

⇒ k = 2\sqrt{2} - 1

So the value of k = 2\sqrt{2} - 1

(iv) p(x) = kx2 - 3x + k

⇒ x - 1 = 0

⇒ x = 1

Putting x = 1 we get,

p(1) = k(1)2 -3(1) + k

= k - 3 + k

⇒ 2k - 3 = 0

⇒ 2k = 3

⇒ k = 32\dfrac{3}{2}

So the value of k = 32\dfrac{3}{2}

Answered By

5 Likes


Related Questions