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Solve the quadratic equation [tex]$3x^2 + 2x - 4 = 0$[/tex].
Give your answers to 2 decimal places.


Sagot :

To solve the quadratic equation [tex]\(3x^2 + 2x - 4 = 0\)[/tex], we can use the quadratic formula:

[tex]\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]

Here, the coefficients are [tex]\(a = 3\)[/tex], [tex]\(b = 2\)[/tex], and [tex]\(c = -4\)[/tex].

Step 1: Calculate the discriminant

The discriminant [tex]\(\Delta\)[/tex] is given by:

[tex]\[ \Delta = b^2 - 4ac \][/tex]

Substitute the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex]:

[tex]\[ \Delta = 2^2 - 4(3)(-4) \][/tex]
[tex]\[ \Delta = 4 + 48 \][/tex]
[tex]\[ \Delta = 52 \][/tex]

Step 2: Calculate the two solutions using the quadratic formula

The solutions are given by:

[tex]\[ x = \frac{-b \pm \sqrt{\Delta}}{2a} \][/tex]

Substitute the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(\Delta\)[/tex]:

[tex]\[ x_1 = \frac{-2 + \sqrt{52}}{2 \cdot 3} \][/tex]
[tex]\[ x_2 = \frac{-2 - \sqrt{52}}{2 \cdot 3} \][/tex]

Step 3: Simplify and find the decimal values

First, we compute [tex]\(\sqrt{52}\)[/tex]:

[tex]\[ \sqrt{52} \approx 7.21 \][/tex]

Substitute this back into the equations for [tex]\(x_1\)[/tex] and [tex]\(x_2\)[/tex]:

[tex]\[ x_1 = \frac{-2 + 7.21}{6} \][/tex]
[tex]\[ x_1 = \frac{5.21}{6} \][/tex]
[tex]\[ x_1 \approx 0.87 \][/tex]

For the second solution:

[tex]\[ x_2 = \frac{-2 - 7.21}{6} \][/tex]
[tex]\[ x_2 = \frac{-9.21}{6} \][/tex]
[tex]\[ x_2 \approx -1.54 \][/tex]

Therefore, the solutions to the quadratic equation [tex]\(3x^2 + 2x - 4 = 0\)[/tex] are:

[tex]\[ x_1 \approx 0.87 \][/tex]
[tex]\[ x_2 \approx -1.54 \][/tex]