# Definitions: Mathematics 11: PTB by Muzzammil Subhan

Definitions from **Textbook of Algebra and Trigonometry Class XI**, published by Punjab Textbook Board (PTB) Lahore, Pakistan. We are very thankful to Muzzammil Subhan for his valuable contribution. Download or view PDF for all definitions. Samples is given below

## Sample

**Exponential Function:**A function in which variable appear as power of a constant is called exponential Function. e.g. $y=2^x$, $y=e^x$**Logarithmic Function:**The functions $f(x)=\log_a x$ and $f(x)=\log_e x$ are called general and natural logarithmic function respectively.**Explicit Function:**If $y$ is easily expressed in term of $x$ then $y$ is called an explicit function. E.g. $y=x^2+3x$**Implicit Function:**If y is not expressed in term of x then y is called an implicit function. E.g. $x^2+xy+y^2=4$**Even Function:**A function is said to be an even function if $f(-x)=f(x)$**Odd Function:**A function is said to be an odd function if $f(-x)=-f(x)$**Circle:**“A set of all points in a plane which are equidistant from a fixed point is called circle.” The fixed point is called centre and fixed distance is called radius of circle.**Point Circle:**A circle whose radius is zero is called point circle.**Parabola:**“A set of all points in a plane which are equidistant from fixed point and fixed line.” The fixed point is called focus and fixed line is called directrix of parabola.**Ellipse:**A set of all points in a plane such that distance of each point from a fixed point bear a constant ratio less then one to the distance from a fixed line.**Hyperbola:**A set of all points in a plane such that distance of each point from a fixed point bear a constant ratio greater then one to the distance from a fixed line.