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28 votes
28 votes
Find the discernment and the numbers of the number of real roots for this equation.
x^2+3x+8=0

User AlexK
by
3.0k points

2 Answers

26 votes
26 votes

Answer: 2 distinct complex solutions (ie non real solutions).

Work Shown:

The given equation is in the form ax^2+bx+c = 0, so

a = 1, b = 3, c = 8

Plug those into the formula below to find the discriminant

D = b^2 - 4ac

D = 3^2 - 4(1)(8)

D = -23

The discriminant is negative, so we get two nonreal solutions. The two solutions are complex numbers in the form a+bi, where a & b are real numbers and
i = √(-1). The two solutions are different from one another.

User Anhtran
by
2.9k points
18 votes
18 votes

Answer:

Discriminant: -23

Number of real roots: 0

Explanation:

For a quadratic in standard form
ax^2+bx+c, the discriminant is given by
b^2-4ac.

In
x^2+3x+8, assign:


  • a\implies 1

  • b\implies 3

  • c\implies 8

The discriminant is therefore:


3^2-4(1)(8)=9-32=\boxed{-23}

For any quadratic:

  • If the discriminant is greater than 0, the quadratic has two real roots
  • If the discriminant is equal to 0, the quadratic has one real root
  • If the discriminant is less than 0, the quadratic as no real roots

Since the quadratic in the question has a discriminant less than 0, there are no real solutions to this quadratic.

User Max Nanasy
by
2.7k points