Without solving, determine the number of real solutions for each quadratic equation.
1. ????^2 − 4???? + 3 = 0
2. 2n^2 + 7 = −4n + 5
3. x − 3x^2 = 5 + 2x − x^2
4. 4???? + 7 = ????^2 − 5???? + 1

Respuesta :

Answer:

1. x^2 − 4x + 3 = 0

[tex] b^2 -4ac = (-4)^2 -4(1)*(3)= 4 >0[/tex] So we have two real solutions

2. 2n^2 + 7 = −4n + 5

[tex] b^2 -4ac = (4)^2 -4(2)*(2)= 0 [/tex] So we just one real solution

3. x − 3x^2 = 5 + 2x − x^2

[tex] b^2 -4ac = (1)^2 -4(2)*(5)= -19 <0 [/tex] No real solutions

4. 4x + 7 = x^2 − 5x + 1

[tex] b^2 -4ac = (-9)^2 -4(1)*(-6)= 105 >0 [/tex] So we have two real solutions

Step-by-step explanation:

1. x^2 − 4x + 3 = 0

We need to compare this function with the general equation for a quadratic formula given by:

[tex] f(x) = ax^2 + bx + c[/tex]

On this case we see that a=1, b = -4 and c =3

We can find the discriminat with the following formula:

[tex] \sqrt{b^2 -4ac}[/tex]

[tex] b^2 -4ac = (-4)^2 -4(1)*(3)= 4 >0[/tex] So we have two real solutions

2. 2n^2 + 7 = −4n + 5

We can rewrite the expression like this:

[tex] 2n^2 +4n +2[/tex]

On this case we see that a=2, b = 4 and c =2

We can find the discriminat with the following formula:

[tex] \sqrt{b^2 -4ac}[/tex]

[tex] b^2 -4ac = (4)^2 -4(2)*(2)= 0 [/tex] So we just one real solution

3. x − 3x^2 = 5 + 2x − x^2

We can rewrite the expression like this:

[tex] 2x^2 +x +5[/tex]

On this case we see that a=2, b = 1 and c =5

We can find the discriminat with the following formula:

[tex] \sqrt{b^2 -4ac}[/tex]

[tex] b^2 -4ac = (1)^2 -4(2)*(5)= -19 <0 [/tex] No real solutions

4. 4x + 7 = x^2 − 5x + 1

We can rewrite the expression like this:

[tex] x^2 -9x -6[/tex]

On this case we see that a=1, b = -9 and c =-6

We can find the discriminat with the following formula:

[tex] \sqrt{b^2 -4ac}[/tex]

[tex] b^2 -4ac = (-9)^2 -4(1)*(-6)= 105 >0 [/tex] So we have two real solutions