Question: find the equation of the line through $(10,-2)$ parallel to a. $4x-2y+1=0$ and b. $x+5y-10=0$
1. **State the problem:** Find the equations of lines passing through the point $(10,-2)$ parallel to the given lines $4x-2y+1=0$ and $x+5y-10=0$.
2. **Find the slope of each given line:**
- For line a: $4x - 2y + 1 = 0$
Rewrite in slope-intercept form $y = mx + b$:
$$4x - 2y + 1 = 0 \implies -2y = -4x - 1 \implies y = \frac{-4x - 1}{-2} = 2x + \frac{1}{2}$$
So, slope $m_a = 2$.
- For line b: $x + 5y - 10 = 0$
Rewrite:
$$5y = -x + 10 \implies y = -\frac{1}{5}x + 2$$
So, slope $m_b = -\frac{1}{5}$.
3. **Use point-slope form for parallel lines:**
The equation of a line with slope $m$ passing through $(x_1,y_1)$ is:
$$y - y_1 = m(x - x_1)$$
4. **Write equations for each line:**
- For line a (slope $2$):
$$y - (-2) = 2(x - 10)$$
$$y + 2 = 2x - 20$$
$$y = 2x - 22$$
- For line b (slope $-\frac{1}{5}$):
$$y - (-2) = -\frac{1}{5}(x - 10)$$
$$y + 2 = -\frac{1}{5}x + 2$$
$$y = -\frac{1}{5}x + 2 - 2$$
$$y = -\frac{1}{5}x$$
5. **Final answers:**
- Line parallel to $4x - 2y + 1 = 0$ through $(10,-2)$ is:
$$y = 2x - 22$$
- Line parallel to $x + 5y - 10 = 0$ through $(10,-2)$ is:
$$y = -\frac{1}{5}x$$