standard_description: Explain why the sum or product of two rational numbers is rational; that the sum of a rational number and an irrational number is irrational; and that the product of a nonzero rational number and an irrational number is irrational.
problem_activity: Write the formula for the functions depicted by the graphs below.
$${f(x)=}$$
$${g(x)=}$$
$${h(x)=}$$
[IMG]


aligns: no