How many solutions does #4x^2 + 8x + 3 = 0# have?

1 Answer
Alan P.
May 1, 2015

The easiest way to determine the answer to your question is to evaluate the #color(red)("discriminant")#
For a quadratic in the form:
#y = ax^2+bx+c#
the #color(red)("discriminant"#) is equal to
#color(red)(b^2-4ac)#

For your example
#4x^2+8x+3=0#
The #color(red)("discriminant")# is
#Delta = (8^2-4(4)(3))/(2(4))#

#Delta=2#

The number of solutions is determined by the value of the #color(red)("discriminant, " Delta)#

#Delta { (>0 " two solutions"),(=0" one solution"),(<0" no solutions"):}#

So
#4x^2+8x+3=0# has two solutions

Further explanation:
The discriminant comes from the formula for quadratic root solutions
#(-b+-sqrt(color(red)(b^2-4ac)))/(2a)#
and it should be fairly obvious from this to understand why

#color(red)(b^2-4ac) { (>0 rarr" two solutions"),(=0 rarr" one solution"),(<0 rarr " no solutions"):}#

Related questions
See all questions in Solutions Using the Discriminant
Impact of this question
4016 views around the world
You can reuse this answer
Creative Commons License