E

**2 + 1/2! + 1/3! + 1/4! + 1/5! + ........... **

**eccentricity:** **A number that indicates
the shape of a conic section. The eccentricity of **

** an**

**ellipse is given by **

**e = sqrt(a^{2} - b^{2})**

a

**element: ** **a member of a set.**

**ellipse: the set of all points in a plane such that the
sum of the distances to two fixed **

** points**

**is a constant. The equation of an ellipse with center
at the origin is**

** x^{2 }+ y^{2 }= 1**

^{ }a^{2 }b^{2}

**ellipsoid: a solid of revolution formed by rotating an
ellipse about one of its axes.**

**empty set:** **a set that contains no elements.**

**equation:** **a mathematical statement that says
that two expressions have the same value.**

**equilateral triangle: a triangle that has three equal
sides.**

**equivalent equations: ** **two equations whose solutions
are the same. For example:**

**x + 3y = 10, and 2x + 6y = 20.**

**even function: a function that satisfies the property
that f(x) = f(-x).**

**even number:** **a natural number that is divisible
by 2.**

**event:** **in probability, a set of outcomes.**

**exponent:** ** a number that indicates the operation
of repeated multiplication.**

**exponential function:** ** a function of the form f(x)
= a ^{x}, where a is a constant known as the
base.**

**extremum:** **a point where a function reaches a maximum
or a minimum.**