How can I find the other root of a quadratic equation with 1 root and a unknown b value?

Question

The information I was given was, "If $6x^2 + kx -42 = 0$ has one root as $\frac{-7}{6}$, then what is the other root?

Answer 1

$$Product\space of\space roots= \frac{-42}{6} =\frac{-7}{6}(x)$$ where $x$ is the unknown root. You get $x=6$ from there.