You might be most familiar with x from math class. Many algebra problems use x as a variable, to stand in for an unknown quantity. But why is x the letter chosen for this role?

Introduces methods of complex variables, contour integration, and theory of residues. Applications include solving partial differential equations by transform methods, Fourier and Laplace transforms, ...

NCERT Class 10 Maths Chapter 3 Pair of Linear Equations in Two Variables: Download the complete chapter in pdf format and refer the same to clear all your concepts.