Tangent Normal Equations
1. **Problem a:** Find the equation of the tangent to the curve $$y=\sqrt{x+1}-a+x=4$$.
2. **Step 1:** Clarify the function. The equation seems ambiguous. Assuming the function is $$y=\sqrt{x+1}-a+x$$ and it equals 4 at some point.
3. **Step 2:** Find the derivative $$y'$$ to get the slope of the tangent.
Given $$y=\sqrt{x+1}-a+x$$, rewrite as $$y=(x+1)^{1/2} - a + x$$.
4. **Step 3:** Differentiate:
$$y' = \frac{1}{2\sqrt{x+1}} + 1$$
5. **Step 4:** Find the point where $$y=4$$:
$$\sqrt{x+1} - a + x = 4$$
Without a specific value for $$a$$, we cannot find exact $$x$$.
6. **Step 5:** The tangent line at point $$x_0$$ has slope $$m = y'(x_0)$$ and passes through $$\left(x_0, y(x_0)\right)$$.
Equation of tangent:
$$y - y(x_0) = m (x - x_0)$$
---
7. **Problem b:** Find the equation of the normal to $$y = x^3 - 5x + 2$$ at $$x = -2$$.
8. **Step 1:** Find $$y(-2)$$:
$$y(-2) = (-2)^3 - 5(-2) + 2 = -8 + 10 + 2 = 4$$
9. **Step 2:** Find derivative $$y'$$:
$$y' = 3x^2 - 5$$
10. **Step 3:** Find slope of tangent at $$x=-2$$:
$$m_{tangent} = 3(-2)^2 - 5 = 3(4) - 5 = 12 - 5 = 7$$
11. **Step 4:** Slope of normal is negative reciprocal:
$$m_{normal} = -\frac{1}{7}$$
12. **Step 5:** Equation of normal line passing through $$(-2,4)$$:
$$y - 4 = -\frac{1}{7}(x + 2)$$
13. **Step 6:** Simplify:
$$y = -\frac{1}{7}x - \frac{2}{7} + 4 = -\frac{1}{7}x + \frac{26}{7}$$
**Final answers:**
- a) Tangent equation depends on $$a$$ and point $$x_0$$ satisfying $$\sqrt{x_0+1} - a + x_0 = 4$$ with slope $$m = \frac{1}{2\sqrt{x_0+1}} + 1$$.
- b) Normal equation:
$$y = -\frac{1}{7}x + \frac{26}{7}$$