Substitute the values for a, b, and c into b2 – 4ac to determine the discriminant. Which quadratic equations will have two real number solutions? (The related quadratic function will have two x-intercepts.) Check all that apply.
0 = 2x2 – 7x – 9
0 = x2 – 4x + 4
0 = 4x2 – 3x – 1
0 = x2 – 2x – 8
0 = 3x2 + 5x + 3

Respuesta :

Answer: [tex]0=2x^2-7x-9\\0=4x^2-3x-1\\0=x^2-2x-8[/tex]


Step-by-step explanation:

We know that the standard quadratic equation is  ax^2+bx+c=0

Let's compare all the given equation to it and , find discriminant.

1. a=2, b= -7, c=-9

[tex]b^2-4ac=(-7)^2-4(2)(-9)=49+72>0[/tex]

So it has 2 real number solutions.

2. a=1, b=-4, c=4

[tex]b^2-4ac=(-4)^2-4(1)(4)=16-16=0[/tex]

So it has only 1 real number solution.

3. a=4, b=-3, c=-1

[tex]b^2-4ac=(-3)^2-4(4)(-1)=9+16=25>0[/tex]

So it has 2 real number solutions.

4. a=1, b=-2, c=-8

[tex]b^2-4ac=(-2)^2-4(1)(-8)=4+32=36>0[/tex]

So it has 2 real number solutions.

5. a=3, b=5, c=3

[tex]b^2-4ac=(5)^2-4(3)(3)=25-36=-9<0[/tex]

Thus it does not has real solutions.



The quadratic equations that has real number solutions are 0 = 4x^2 – 3x – 1, 0 = x^2 – 2x – 8 and 2x^2 – 7x – 9

Discriminant

The formula for finding the discriminant is [tex]b^2-4ac[/tex]

  • Any quadratic equation has real number solutions if the discriminant is greater than zero.

For the quadratic equation [tex]2x^2 - 7x - 9 = 0[/tex]

[tex]b^2-4ac = (-7)^2-4(2)(-9) = 49 + 72 =121 [/tex]

This equation will have two real number solutions

For the quadratic equation [tex]4x^2 - 3x - 1 = 0[/tex]

[tex]b^2-4ac = (-3)^2-4(4)(-1) = 9 + 16 =25 >0[/tex]

This equation will have two real number solutions

For the quadratic equation [tex]x^2 - 2x - 8 = 0[/tex]

[tex]b^2-4ac = (-2)^2-4(1)(-8) = 4 + 32 =36>0 [/tex]

This equation will have two real number solutions

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