Factorise:
`ar + br + at + bt`

The sum of first r terms of a series is ar^(2) + br , find the first and 12th terms of the series.

Factorisation - How to Factorise?

In P is a point in the interior of a parallelogram ABCD. Show that (ii) ar (APD) + ar (PBC) = ar (APB) + ar (PCD)

In, PQRS and ABRS are parallelograms and X is any point on side BR. Show that ar (PQRS) = ar (ABRS) as (AXS) = (1)/(2) ar (PQRS)

PQRS and ABRS are parallelograms and X is any point on the side BR. Show that ar (Delta AXS) = (1)/(2) ar (PQRS)

PQRS and ABRS are parallelograms and X is any point on the sides BR. Show that ar(PQRS)=ar(ABRS)

Draw Lewis symbols for the following elements : B, Ge, Si, Ar, Ca, K, As, Br.