Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If ( x + 2) and (x - 3) are the factors of $x^2 +k_1x + k_2$, then :

Options:

$k_1 = 1$ and $k_2 = -6$

$k_1 = -1$ and $k_2 = -6$

$k_1 = -1$ and $k_2 = 6$

$k_1 = 1$ and $k_2 = 6$

Correct Answer:

$k_1 = 1$ and $k_2 = -6$

Explanation:

If ( x - 2) and (x + 3) are the factors of $x^2 +k_1x + k_2$ then,

Putting x = 2 in the given equation, we get

= 22 + 2k1 + k2 = 0

⇒ 2k1 + k2 = - 4      …..(A)

Similarly, Putting x = -3 in the given equation,

= (-3) 2 - 3k1 + k2 = 0

= - 3k1 + k2 = -9      ……(B)

Subtracting (A) and (B)

= 5k= 5

= k1 = 1

Putting value of k1 in (A)

= k2 = -6

k1 = 1 and k2 = -6