Can you please help me simplify (1+4i)^2

Bismuth-210 is an isotope that radioactively decays by about 13% each day, meaning 13% of the remaining bismuth-210 transforms into another atom (polonium-210 in this case) each day. if you begin with 233 mg of bismuth-210, how much remains after 8 days?

What is the equation of this graphed line? enter your answer in slope-intercept form in the box.

Which compound inequality could be represented by the graph?