Question

$f(x) = −3x2−11x+7$

Answer 1

Answer:

$x= \frac{ - 11 + \sqrt{205} }{6} \: \: \: \: \: or \: \: \: \: \\x = \frac{ - 11 - \sqrt{205} }{6}$

Step-by-step explanation:

$- 3x {}^{2} - 11x + 7 = 0 \\ 3x {}^{2} + 11x - 7 = 0$

here,

$a = 3 \\ b = 11 \\ c = - 7$

now,

$D = b {}^{2} - 4ac \\ = (11) {}^{2} - 4(3)( - 7) \\ = 121 + 84 \\ = 205 > 0$

so,

$x = \frac{ - b + - \sqrt{b {}^{2} - 4ac} }{2a} \\ \\ = \frac{ - 11 + - \sqrt{205} }{2(3)} \\ = \frac{ - 11 + - \sqrt{205} }{6} \\ \\ = \frac{ - 11 + \sqrt{205} }{6} \: \: \: \: \: or \: \: \: \: = \frac{ - 11 - \sqrt{205} }{6}$