DDesmos SAT Prep
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Exponential Growth & Decay

Evaluate or solve exponential models using tables and intersections.

The Desmos trick

Graph the exponential model, then use the table feature to read off its value at a specific time, or graph a horizontal line at a target value and find the intersection to solve for time.

  • Type the model exactly: y = 500(1.08)^x
  • Use the table to evaluate at a specific x without a calculator
  • To solve for when the model hits a target value, graph y = (target) and click the intersection

Practice questions

Q1A population is modeled by P(t) = 500(1.08)^t, where t is years. To th…
Medium
Q2A radioactive substance decays according to A(t) = 200(0.5)^(t/5), whe…
Hard
Q3A population is modeled by A(t) = 1000(0.9)^t, where t is years. To th…
Easy
Q4Using the same model A(t) = 1000(0.9)^t, what is the smallest whole nu…
Hard