state gov RPSC 2nd Grade Senior Teacher Mock Test Series 2025 Engineering Mathematics Calculus Vector Calculus
If \( \rm \vec r=x\hat i+y\hat j+z\hat k \ and \ r = \sqrt{x^2+y^2+z^2}\), then \(\rm grad\left(\frac{1}{r}\right)\) is equal to:
1
\(\rm -\frac{\vec r}{r^3}\)
2
\(\rm -\frac{\vec r}{r^2}\)
3
\(\rm \frac{\vec r}{r^3}\)
4
\(\rm \frac{\vec r}{r}\)
5
Question Not Attempted