What is linear equation???

an equation between two variables that gives a straight line when plotted on a graph. In mathematics, a linear equation is an equation that may be put in the form {\displaystyle a_{1}x_{1}+\cdots +a_{n}x_{n}+b=0, } where x_{1}, \ldots, x_{n} are the variables, and {\displaystyle b, a_{1}, \ldots, a_{n}} are the coefficients, which are often real numbers.