Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

If $\frac{d}{dx}[ax^3+ ax^2 + ax + 1] = 9x^2 + 6x +3$, then $a$ is equal to

Options:

1

2

3

4

Correct Answer:

3

Explanation:

The correct answer is Option (3) → 3

$\frac{d}{dx}[ax^{3}+ax^{2}+ax+1]=3ax^{2}+2ax+a$

$3ax^{2}+2ax+a=9x^{2}+6x+3$

$\Rightarrow\;3a=9,\;2a=6,\;a=3$

$a=3$