A square matrix $$B$$ is symmetric if ____

In the solution of the following set of linear equations by Gauss-elimination using partial pivoting $$$5x+y+2z=34,$$$ $$$4y-3z=12$$$ and $$$10x-2y+z=-4.$$$
The pivots for elimination of $$x$$ and $$y$$ are

In quadrantal bearing system, bearing of a line varies from

An agricultural land of 437ha is to be irrigated for a particular crop. The base period of the crop is 90 days and the total depth of water required by the crop is 105cm. If a rainfall of 15cm occurs during the base period, the duty of irrigation water is