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Find the smaller root of [tex]$3x^2 - 14x - 5 = 0$[/tex].

A. -5
B. 5
C. 3
D. [tex]\frac{1}{3}[/tex]
E. [tex]-\frac{1}{3}[/tex]


Sagot :

To find the roots of the quadratic equation [tex]\(3x^2 - 14x - 5 = 0\)[/tex], we use the quadratic formula:

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

Here, the coefficients are [tex]\(a = 3\)[/tex], [tex]\(b = -14\)[/tex], and [tex]\(c = -5\)[/tex]. Substituting these into the quadratic formula:

[tex]\[ x = \frac{-(-14) \pm \sqrt{(-14)^2 - 4 \cdot 3 \cdot (-5)}}{2 \cdot 3} \][/tex]

Simplify the terms inside the square root:

[tex]\[ x = \frac{14 \pm \sqrt{196 + 60}}{6} \][/tex]

[tex]\[ x = \frac{14 \pm \sqrt{256}}{6} \][/tex]

Since [tex]\(\sqrt{256} = 16\)[/tex]:

[tex]\[ x = \frac{14 \pm 16}{6} \][/tex]

This gives us two potential roots:

[tex]\[ x = \frac{14 + 16}{6} = \frac{30}{6} = 5 \][/tex]

[tex]\[ x = \frac{14 - 16}{6} = \frac{-2}{6} = -\frac{1}{3} \][/tex]

The roots are [tex]\(5\)[/tex] and [tex]\(-\frac{1}{3}\)[/tex].

Among these, the smaller root is [tex]\(-\frac{1}{3}\)[/tex].

Thus, the correct answer is:

[tex]\[ \boxed{-\frac{1}{3}} \][/tex]