A study by the Partnership for a Drug-Free America indicated that, in 1998, 42% of teens in grades 7 though 12 had recently used cigarettes. A similar study in 2005 indicated that 22% of such teens had recently used cigarettes. Write a linear model that relates the percent of teens that recently used cigarettes y to the number of years after 1998, x.

Question

A study by the Partnership for a Drug-Free America indicated that, in 1998, 42% of teens in grades 7 though 12 had recently used cigarettes.  A similar study in 2005 indicated that 22% of such teens had recently used cigarettes.  Write a linear model that relates the percent of teens that recently used cigarettes y to the number of years after 1998, x.

hero · Answer

Plot points (0,42) and (7,22), then find slope and use point slope formula to obtain the linear model

anonymous · Answer

a self -catalytic chemical reaction results in the formation of a compound that causes the formation ratio to increases.If the reaction rate V is given V(x)=kx(a-x)where k is a positive constant , a is initial amount of the compound,and x is the variable amount of the compound,for what value of x is the reaction rate maximum?use the properties of the graph of the quadratic function.