Chapter 5.1, Problem 30E

To determine

To find: the slope and y-intercept

Answer to Problem 30E

The slope is $\text{m}=20$

The y intercept is $280

Explanation of Solution

Given:

  $y=25x+250,$

Calculation:

Friend's equation is in slope-intercept form where: $m=25,b=250$

The graph will be:

  

Find the amount of friend's account after 6 months by solving for $y$ when $x=6$ :

  $y=25(6)+250$

  $y=400(\$400)$

Therefore, our goal is to have a linear equation that passes through point (6,400)

POSSIBLE ANSWER:

Use point-slope form:

  $y-y_1=m\left(x-x_2\right)$

Let $\text{m}=20$ substitute the point:

  $y-400=20(x-6)$

  $y-400=20x-120\leftarrow$ Add 400

  $y=20x+280$

The slope $(\text{m}=20)$ is the monthly increase of account at $ 20 per month.

The y intercept is the initial account at $280(0 months ).

Conclusion:

The slope is $\text{m}=20$

The y intercept is $280