Value of \(\int_{-4}^{4}\displaystyle |x+2|\,dx\) is :
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 20
The expression x + 2 changes sign at x = −2, so the modulus is removed separately on each side of it:
\(|x+2| = -(x+2)\) for \(-4 \le x \le -2\)
\(|x+2| = x+2\) for \(-2 \le x \le 4\)
So
\( \displaystyle \int_{-4}^{4}|x+2|\,dx = \int_{-4}^{-2}-(x+2)\,dx + \int_{-2}^{4}(x+2)\,dx \)
\( \displaystyle = \left[-\frac{(x+2)^2}{2}\right]_{-4}^{-2} + \left[\frac{(x+2)^2}{2}\right]_{-2}^{4} \)
\( \displaystyle = \left(0 + \frac{4}{2}\right) + \left(\frac{36}{2} - 0\right) \)
\( = 2 + 18 = 20 \)