Line Perpendicular De7Af0
1. **State the problem:**
We have a line L given by the equation $$4y + 12 = 16x$$ and a line R that is perpendicular to L and passes through the point $(-1, 5)$. We need to:
a) Find the equation of line R.
b) Find the intersections of lines L and R with the coordinate axes.
c) Determine the monotony (increasing or decreasing behavior) of line R.
2. **Rewrite line L in slope-intercept form:**
Start with $$4y + 12 = 16x$$
Subtract 12 from both sides:
$$4y = 16x - 12$$
Divide both sides by 4:
$$y = 4x - 3$$
So, the slope of line L is $$m_L = 4$$.
3. **Find the slope of line R:**
Since R is perpendicular to L, its slope $$m_R$$ satisfies:
$$m_R = -\frac{1}{m_L} = -\frac{1}{4}$$
4. **Find the equation of line R passing through $(-1, 5)$:**
Use point-slope form:
$$y - y_1 = m_R (x - x_1)$$
Substitute $$m_R = -\frac{1}{4}$$, $$x_1 = -1$$, $$y_1 = 5$$:
$$y - 5 = -\frac{1}{4}(x + 1)$$
Simplify:
$$y - 5 = -\frac{1}{4}x - \frac{1}{4}$$
Add 5 to both sides:
$$y = -\frac{1}{4}x - \frac{1}{4} + 5 = -\frac{1}{4}x + \frac{19}{4}$$
So, the equation of line R is:
$$y = -\frac{1}{4}x + \frac{19}{4}$$
5. **Find intersections with coordinate axes:**
- For line L: $$y = 4x - 3$$
- **x-intercept:** Set $$y=0$$:
$$0 = 4x - 3 \Rightarrow 4x = 3 \Rightarrow x = \frac{3}{4}$$
So, x-intercept is $$\left(\frac{3}{4}, 0\right)$$.
- **y-intercept:** Set $$x=0$$:
$$y = 4(0) - 3 = -3$$
So, y-intercept is $$(0, -3)$$.
- For line R: $$y = -\frac{1}{4}x + \frac{19}{4}$$
- **x-intercept:** Set $$y=0$$:
$$0 = -\frac{1}{4}x + \frac{19}{4} \Rightarrow -\frac{1}{4}x = -\frac{19}{4} \Rightarrow x = 19$$
So, x-intercept is $$(19, 0)$$.
- **y-intercept:** Set $$x=0$$:
$$y = -\frac{1}{4}(0) + \frac{19}{4} = \frac{19}{4} = 4.75$$
So, y-intercept is $$(0, \frac{19}{4})$$.
6. **Determine the monotony of line R:**
Since the slope $$m_R = -\frac{1}{4} < 0$$, line R is **decreasing**.
**Final answers:**
- a) Equation of line R: $$y = -\frac{1}{4}x + \frac{19}{4}$$
- b) Intersections:
- Line L: x-intercept $$\left(\frac{3}{4}, 0\right)$$, y-intercept $$(0, -3)$$
- Line R: x-intercept $$(19, 0)$$, y-intercept $$(0, \frac{19}{4})$$
- c) Line R is decreasing because its slope is negative.