x = 1.75 or − 0.15
x = 2.12 or − 0.79
x = 1.5 or − 0.34
x = 2.35 or −1.23
Correct answer is B
Using the quadratic formula, we have
x=−b±√b2−4ac2a
From the equation 3x2−4x−5=0, a = 3, b = -4 and c = -5.
∴
= \frac{4 \pm \sqrt{16 + 60}}{6}
= \frac{4 \pm \sqrt{76}}{6}
= \frac{4 \pm 8.72}{6}
= \frac{4 + 8.72}{6} \text{ or } \frac{4 - 8.72}{6}
= \frac{12.72}{6} \text{ or } \frac{-4.72}{6}
x = \text{2.12 or -0.79}