Find a number when multiplied by radical 2 increases by 2

If g(x) is an odd function, which function must be an even function?

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )