Polynomials
NCERT Exemplar
CBSE
Grade 10
Question:
If one zero of the quadratic polynomial $x^2 + 3x + k$ is $2$, then the value of $k$ is:
(a) $10$
(b) $-10$
(c) $-7$
(d) $-2$
Step-by-Step Solution
Key Concept: Substitute $x = 2$ into $p(x) = 0$.
$p(2) = 2^2 + 3(2) + k = 0$. [0.5 Mark]
$4 + 6 + k = 0 \Rightarrow 10 + k = 0 \Rightarrow k = -10$. [0.5 Mark]
---
🎯 Official CBSE Marking Scheme:
Substituting zero into polynomial: 0.5 Mark
Solving for $k$: 0.5 Mark
Correct Answer: $-10$
Confused by the solution? Ask the AI to explain a specific step, tell you where you went wrong, or break down the key trap in this question.