4.3B Exponential Growth Equations

Using the rule of 72 how many years will it take to turn $300 into $600 at an interest rate of 8%?

We have an initial investment of $1,000 we will invest at 8%.

How many years will it take to double?

$$f\left(x\right)=1,000\left(2\right)^{\frac{x}{9}}$$

We have an initial investment of $1,000 we will invest at 8%.

How many years will it take to quadruple (double twice)?

$$f\left(x\right)=1,000\left(2\right)^{\frac{x}{9}}$$

We have an initial investment of $1,000 we will invest at 8%.

How many years will it take to octuple (double three times)?

$$f\left(x\right)=1,000\left(2\right)^{\frac{x}{9}}$$

Is $$f\left(x\right)=100\left(.2\right)^x$$ growth or decay?

Which of the following is an example of exponential growth?

$$f\left(x\right)=100\left(.2\right)^x$$

This equation represents _% being (added/subtracted) from the total every t years.

$$f\left(x\right)=100\left(1.4\right)^x$$

This equation represents _% being (added/subtracted) from the total every t years.

$$f\left(x\right)=100\left(.85\right)^x$$

This equation represents _% being (added/subtracted) from the total every t years.