Isaiah is standing in a stadium and has the option of running up a staircase or down a staircase for exercise. The function f(x)=\frac{1}{25}\big(\left|7x\righ t|+5x\big)f(x)=251(∣7x∣+5x) will determine how many calories Isaiah will burn if he runs up xx steps. Use a negative value for xx if he runs down the stairs. Find and interpret the given function values and determine an appropriate domain for the function.