1. **State the problem:** We have two polynomial functions:
$$y_1 = (x + a)^2 + b$$
$$y_2 = cx^3 + d$$
Given that $y_2$ crosses the x-axis at $x = -1$ and the y-axis at $y = 2$, and that $y_1$ and $y_2$ are equal and tangent at $x = 1$, we need to find the values of $a$, $b$, $c$, and $d$.
2. **Use the given conditions:**
- Since $y_2$ crosses the x-axis at $x = -1$, then $y_2(-1) = 0$:
$$c(-1)^3 + d = -c + d = 0 \implies d = c$$
- Since $y_2$ crosses the y-axis at $y = 2$, then $y_2(0) = d = 2$:
$$d = 2$$
From above, $d = c$ and $d = 2$, so:
$$c = 2, \quad d = 2$$
3. **Equality and tangency at $x = 1$:**
- The functions are equal at $x=1$:
$$y_1(1) = y_2(1)$$
- They are tangent at $x=1$, so their derivatives are equal at $x=1$:
$$y_1'(1) = y_2'(1)$$
4. **Calculate $y_1(1)$ and $y_2(1)$:**
$$y_1(1) = (1 + a)^2 + b$$
$$y_2(1) = c(1)^3 + d = c + d = 2 + 2 = 4$$
Set equal:
$$(1 + a)^2 + b = 4$$
5. **Calculate derivatives:**
$$y_1'(x) = 2(x + a)$$
$$y_2'(x) = 3cx^2$$
At $x=1$:
$$y_1'(1) = 2(1 + a)$$
$$y_2'(1) = 3c(1)^2 = 3c = 3 \times 2 = 6$$
Set equal:
$$2(1 + a) = 6 \implies 1 + a = 3 \implies a = 2$$
6. **Substitute $a=2$ into the equality equation:**
$$(1 + 2)^2 + b = 4 \implies 3^2 + b = 4 \implies 9 + b = 4 \implies b = 4 - 9 = -5$$
7. **Check $y_2$ crosses x-axis at $x=-1$:**
$$y_2(-1) = c(-1)^3 + d = -c + d = -2 + 2 = 0$$
This matches the condition.
**Final values:**
$$a = 2, b = -5, c = 2, d = 2$$
**Answer corresponds to option D.
Polynomial Parameters
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.