In the quadratic equation \[x^2 + \left(k-\frac{1}{k}\right)x - 1 = 0,\]solve for $x$ in terms of $k$.

When you arrive at the lake, your friend realises he hasn’t got any swimming trunks. you need to ride to a sports shop. the sports shop is 8350 metres away. how many metres is it to cycle there and back?

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

Check all that apply. f is a function. f is a one-to-one function. c is a function. c is a one-to-one function.