Suppose that a cell phone monthly rate plan costs the user 5 cents per minute beyond a fixed monthly fee of $20. This implies th
at the relationship between monthly cost and monthly number of minutes is linear. Write an equation in words that relates total monthly cost to monthly minutes used.
Equation of a tangent line of a curve is: y- y0 = f´ (x0) (x - x0 ). In this case: x0=1, y0=1 f´(x)=(Derivation) f´(x0)= y - 1 = 1/2 ( x - 1 ) y - 1 = 1/2 x - 1/2 y = 1/2 x - 1/2 + 1 y =