Let $ a_0, a_1, ..., a_{23} $ be real numbers such that $$ \left(1 + \frac{2}{5}x \right)^{23} = \sum_{i=0}^{23} a_i x^i $$ for every real number $ x $. Let $ a_r $ be the largest among the numbers $ a_j $ for $ 0 \leq j \leq 23 $. Then the value of $ r $ is ________.
A temperature difference can generate e.m.f. in some materials. Let $ S $ be the e.m.f. produced per unit temperature difference between the ends of a wire, $ \sigma $ the electrical conductivity and $ \kappa $ the thermal conductivity of the material of the wire. Taking $ M, L, T, I $ and $ K $ as dimensions of mass, length, time, current and temperature, respectively, the dimensional formula of the quantity $ Z = \frac{S^2 \sigma}{\kappa} $ is:
It is a set of 3 mutually perpendicular axes and a convenient way to represent a set of numbers (2 or 3) or a point in space.
Hence, we have a way to represent an imaginary number graphically. All we need to do is to find the real part and an imaginary part of it. Then, represent them on the two mutually perpendicular number lines. The point of intersection, as shown in the above diagram, is the origin of our Plane.
The formation of the Plane so formed is known as the Argand Plane and it is a convenient way to represent an imaginary number graphically.