The Quadratic Formula

The technique of completing the square deserve to be applied to any type of quadratic polynomial.

You simply rewrite ax2+bx+c = a(x2+


From it us can obtain the following result:

The roots of ax2+bx+c are given by

(Quadratic Formula)

The quantity b2−4ac is dubbed the discriminant that the polynomial.

If b2−4ac the equation has actually no actual number solutions, yet it walk have complicated solutions. If b2−4ac = 0 the equation has actually a repeated actual number root. If b2−4ac > 0 the equation has two distinctive real number roots.


Study some of these examples:

You are watching: Square root of b^2-4ac

uncover the root of x2 + x + = 0

x =
± sqrt( 2 − 4× × )

x =
± sqrt( )

x =


x2 + x +

b2 - 4ac =


x1 = , x2 =


Now shot some of this exercises:

The root of x2 + x + are:

Working area:

Parabola Vertex

Note that if the roots of a quadratic equationax2+bx+c space real and distinct, climate the peak of the parabola offered by the polynomial is positioned where



Study a few of this examples:

Locating the crest of the parabola offered by x2 + x + :

The x-coordinate is

x =


Substituting this value of x right into the given equation we find:

the y-coordinate is ( )2 + ( ) + =

Hence the vertex is ( , )


Now try some of these exercises. Provide your answer rounded come 2 decimal places:

locate the crest of the parabola given by x2 + x + :

Working area:

The crest is ( , )

If the roots of a quadratic equation ax2+bx+c are α and also β, then we can write ax2+bx+c = a(x−α)(x−β)

completing the Square | Quadratic Polynomials index | Quadratic functions Factoriser >>

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