Solve by the most appropriate method.
-$7 k ^ { 2 } - 5 k - 5 = 0$
A) $k = \frac { 5 \pm \sqrt { 95 } } { 28 }$
B) $k = \frac { - 5 \pm \sqrt { 165 } } { 14 }$
C) $k = \frac { 5 \pm \sqrt { 165 } } { 7 }$
D) $\mathrm { k } = \frac { 5 \pm \sqrt { 165 } } { 14 }$

Question

Quizplus · Accepted Answer

The quadratic formula $\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$ is used to solve $7k^2 - 5k - 5 = 0$, where $a = 7$, $b = -5$, and $c = -5$. Substituting these values into the formula gives $k = \frac{5 \pm \sqrt{(-5)^2 - 4(7)(-5)}}{2(7)} = \frac{5 \pm \sqrt{25 + 140}}{14} = \frac{5 \pm \sqrt{165}}{14}$, which matches option D.

Solve by the Most Appropriate Method 7k2−5k−5=07 k ^ { 2 } - 5 k - 5 = 07k2−5k−5=0

Solve by the Most Appropriate Method $7 k ^ { 2 } - 5 k - 5 = 0$