Question

If $y = 3x^2 + 2$ and if x changes from 10 to 10.1, then the approximate change in y will be?

• A. 4
• B. 5
• C. 6
• D. 8

Answer 1

Answer: (C)

6

Answer 2

Given equation is $y = 3x^2 + 2$ $\frac{dy}{dx} = 6x$ Let small charge in x be $\Delta x$ and corresponding change in y is $\Delta y$. $\frac{dy}{dx} = \frac{\Delta y}{\Delta x} \Rightarrow \frac{\Delta y}{\Delta x} = 6x$ $\Delta y =6x . \Delta x$ $\Delta x = 0.1$ and $x = 10$ $\Rightarrow \Delta y = 6 \times10 \times0.1 = 6$