Question

If (x-3) is a factor of polynomial
$(2x {}^{2} + x + k)$
find k.​

Answer 1

Answer:

-21

Step-by-step explanation:

if x- 3

x=3

put the value of x in equation

2(3^2)+3+k

18+3+k

k=-21

Answer 2

• The value of k is (-21)

Step-by-step explanation:

Given:

• P(x) = 2x² + x + k

• (x - 3) is a factor of P(x)

To find

The value of k, for which (x - 3) becomes the factor of the given polynomial P(x)

So,

⇒ x - 3 = 0

⇒ x = 3

[∵ Taking 3 to RHS]

Thus, 3 is a zero of the polynomial

Now, we can get that,

P(3) = 0

⇒ 2(3)² + (3) + k = 0

⇒ 2 * 9 + 3 + k = 0

⇒ 18 + 3 + k = 0

⇒ 21 + k = 0

⇒ k = -21

[By taking 21 to RHS]