Introductory Algebra

quadratic equation • A quadratic equation is an

equation that can be written in the form ax2 + bx + c = 0, where a, b, and c are real numbers,with a 0.

discriminant • The quantity under the radical in the

quadratic formula, b2 - 4ac.

complex number • Any number that can be written in

the form a + bi, where a and b are real numbers.

imaginary number • A complex number a + bi • with b 0.

real part • The real part of a complex • number a + bi is a.

imaginary part • The imaginary part of the • complex number a + bi is b.

standard form of a complex number

• The standard form of a • complex number is a + bi.

conjugate of a complex number

• The conjugate of a complex • number a + bi is a - bi.

parabola • The graph of a second-degree

(quadratic) equation in two variables is called a parabola.

parabola • The graph of a second-degree

(quadratic) equation in two variables is called a parabola.

axis (axis of symmetry)

• The axis of a parabola is thevertical or horizontal line through the vertex of the parabola.

quadratic function • A function defined by an equation of

the form f(x) = ax2 + bx + c, for real numbers a, b, and c, with a 0.