Model radioactive decay using the notation t = time (independent variable), r(t) = amount of particular radioactive isotope present at time t (dependent variable), = decay rate (parameter). Note that the minus sign is used so that > 0. (a) Using this notation, write a model for the decay of a particular radioactive isotope. (b) If the amount of the isotope present at t = 0 is r0, state the corresponding initial-value problem for the model in part (a).

1.1 Lines ● A l ine is determined by two points. ● A line is given by a formula. ○ Pointslope form ○ Slopeintercept form Point Slope Formula y − y = m (x − x ) 1 1 where m is slope and x 1d y a1 a point (x ,1 1 Slope is the change of y, divided by the change of x. m = y 1 y2 1 x2