The discriminant indicated usually by #Delta#, is a part of the quadratic formula provided to solve second degree equations.Given a 2nd degree equation in the general form:#ax^2+bx+c=0#the discriminant is:#Delta=b^2-4ac#

The discriminant deserve to be offered to characterize the options of the equation as:1) #Delta>0# two separate real solutions;2) #Delta=0# two coincident actual solutions (or one repeated root);3) #Delta no real solutions.

You are watching: B^2-4ac=0 how many solutions

For example:#x^2-x-2=0#Where: #a=1#, #b=-1# and #c=-2#So:#Delta=b^2-4ac=1+4*2=9>0#, offering #2# real unique solutions.

The discriminant can additionally come in handy once attempting to factorize quadratics. If #Delta# is a square number, climate the quadratic will factorize, (since the square source in the quadratic formula will certainly be rational). If it is not a square number, climate the quadratic will certainly not factorize. This deserve to save friend spending eras trying come factorize when it won"t work. Instead, deal with by perfect the square or using the formula.

I hope that helps!


Answer link
*

George C.
Dec 5, 2017

See explanation...


Explanation:

The discriminant the a polynomial equation is a worth computed from the coefficients which helps us recognize the type of root it has actually - especially whether they are actual or non-real and distinct or repeated.

Quadratic equations

The discriminant #Delta# the a quadratic equation with real coefficients in typical form:

#ax^2+bx+c = 0#

is given by the formula:

#Delta = b^2-4ac#

From the discriminant we deserve to discriminate even if it is the equation has two actual roots, one repeated real root or 2 non-real roots.

If #Delta > 0# climate the quadratic equation has two distinct real roots.If #Delta = 0# climate the quadratic equation has one repeated genuine root.If #Delta then the quadratic equation has no genuine roots. It has actually a facility conjugate pair the non-real roots.

Cubic equations

For a cubic equation with real coefficients in traditional form:

#ax^3+bx^2+cx+d = 0#

the discriminant #Delta# is provided by the formula:

#Delta = b^2c^2-4ac^3-4b^3d-27a^2d^2+18abcd#

If #Delta > 0# then the cubic equation has three actual roots.If #Delta = 0# climate the cubic has actually a repetitive root. It may have actually one actual root of multiplicity #3#. Otherwise the may have actually two unique real roots, among which is the multiplicity #2#.If #Delta then the cubic equation has actually one actual root and a facility conjugate pair of complex roots.

See more: Why Was The Steel Plow Important, Why Was The Steel Plow Better Than The Old Plow

Higher degree

Polynomial equations of higher degree also have discriminants, which assist determine the nature the the roots, however they space less useful for quartics and also above.