1. **Stating the problem:**
Find the equation of a line using different methods:
(a) Two points
(b) Slope and a point
(c) Slope and y-intercept
(d) X- and y-intercepts
2. **Formula and rules:**
- Slope formula between two points $(x_1,y_1)$ and $(x_2,y_2)$ is:
$$m = \frac{y_2 - y_1}{x_2 - x_1}$$
- Point-slope form of a line:
$$y - y_1 = m(x - x_1)$$
- Slope-intercept form:
$$y = mx + b$$ where $b$ is the y-intercept.
- To find the equation from x- and y-intercepts $(a,0)$ and $(0,b)$:
$$\text{slope } m = \frac{0 - b}{a - 0} = -\frac{b}{a}$$
Equation:
$$y = m x + b$$
3. **(a) Using two points:**
Choose points $(5,770)$ and $(15,2270)$ from the problem.
Calculate slope:
$$m = \frac{2270 - 770}{15 - 5} = \frac{1500}{10} = 150$$
Use point-slope form with point $(5,770)$:
$$y - 770 = 150(x - 5)$$
Simplify:
$$y - 770 = 150x - 750$$
$$y = 150x + 20$$
4. **(b) Using slope and a point:**
Given slope $m=150$ and point $(15,2270)$:
$$y - 2270 = 150(x - 15)$$
Simplify:
$$y - 2270 = 150x - 2250$$
$$y = 150x + 20$$
5. **(c) Using slope and y-intercept:**
Given slope $m=150$ and y-intercept $b=20$:
Equation is directly:
$$y = 150x + 20$$
6. **(d) Using x- and y-intercepts:**
From the equation $y = 150x + 20$, find x-intercept by setting $y=0$:
$$0 = 150x + 20$$
$$150x = -20$$
$$x = \frac{-20}{150} = -\frac{2}{15}$$
So x-intercept is $\left(-\frac{2}{15}, 0\right)$ and y-intercept is $(0,20)$.
Calculate slope:
$$m = \frac{0 - 20}{-\frac{2}{15} - 0} = \frac{-20}{-\frac{2}{15}} = -20 \times -\frac{15}{2} = 150$$
Equation:
$$y = 150x + 20$$
**Final answer:** The equation of the line is
$$y = 150x + 20$$
This equation is consistent across all methods.
Line Equation Bd981F
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