Question

The largest value of 2x³ – 3x² – 12x + 10 for – 2 £ x £ 4 occurs at x =

• A. – 2
• B. – 1
• C. 2
• D. 4

Answer 1

Answer: (D)

4

Answer 2

$\frac{dy}{dx}$= 6x² – 6x – 12 ̃ 6 (x² – x – 2)= 0

x = 2, – 1

$\left. \ \begin{aligned} & f(2) = 16–3 \times 4–12 \times 2 + 10 = –10 \\ & f(–1) = –2–3 + 12 + 10 = 17 \\ & f(–2) = –16–12 + 24 + 10 = 6 \\ & f(4) = 128–48–48 + 10 = 42 \end{aligned} \right\rbrack$largest value occur at x = 4