Polynomial Geometry
1. **Problem statement:**
We have several algebraic expressions and geometric questions to solve.
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2. **Part a:** Simplify polynomial $A$.
Given $A = x^2 + y^2 + xy$, it is already simplified.
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3. **Part b:** Determine the degree of polynomial $A$.
The degree of a polynomial is the highest sum of exponents in any term.
For $A = x^2 + y^2 + xy$, the degrees of terms are:
- $x^2$: degree 2
- $y^2$: degree 2
- $xy$: degree $1+1=2$
So the degree of $A$ is 2, not 3 as stated.
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4. **Part c:** Define $C = A + B$ and simplify.
Given $C = x^2 + y^2 - 2xy$ after simplification.
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5. **Part d:** Evaluate $C$ at $x=6$, $y=7$.
Calculate:
$$C = 6^2 + 7^2 - 2 \times 6 \times 7 = 36 + 49 - 84 = 1$$
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6. **Multiple choice question 12:**
Rectangle with width $x+3$ and length $x-3$, $x>3$.
Area $= (x+3)(x-3) = x^2 - 9$ (m²).
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7. **Essay question 1a:** Group monomials by like terms.
Monomials:
- $3.5y$, $y$, $-5y$ (like terms with $y$)
- $4x^3 y^{2/3}$, $9x^3 y^{2/3}$ (like terms)
- $-0.5x^2 y$ (unique)
- $\frac{3}{4} x y^{3/4}$ (unique)
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8. **Essay question 1b:** Perform division:
$$\frac{10x^3 y^2 - 5x^2 y + 25xy}{5xy} = \frac{10x^3 y^2}{5xy} - \frac{5x^2 y}{5xy} + \frac{25xy}{5xy} = 2x^2 y - x + 5$$
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9. **Essay question 2a:** Given $M = 2x^2 + 4xy - 2y^2 - 4$, $N = 3x^2 - 2xy + 2y^2$.
Find $P = M + N$:
$$P = (2x^2 + 4xy - 2y^2 - 4) + (3x^2 - 2xy + 2y^2) = (2x^2 + 3x^2) + (4xy - 2xy) + (-2y^2 + 2y^2) - 4 = 5x^2 + 2xy - 4$$
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10. **Essay question 2b:** Evaluate $P$ at $x=1$, $y=-2$:
$$P = 5(1)^2 + 2(1)(-2) - 4 = 5 - 4 - 4 = -3$$
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11. **Essay question 3a:** Given triangle $ABC$, $M$ between $B$ and $C$, $N$ on $AB$, $P$ on $AC$ such that $MN \parallel AC$ and $MP \parallel AB$.
Quadrilateral $ANMP$ has both pairs of opposite sides parallel, so it is a parallelogram.
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12. **Essay question 3b:** For $ANMP$ to be a rhombus, $M$ must be positioned so that all sides are equal in length.
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13. **Essay question 3c:** For $ANMP$ to be a square, triangle $ABC$ must be right-angled and isosceles with $M$ at the midpoint of $BC$.
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**Final answers:**
- a) $A = x^2 + y^2 + xy$
- b) Degree of $A$ is 2
- c) $C = x^2 + y^2 - 2xy$
- d) $C(6,7) = 1$
- Question 12: Area $= x^2 - 9$
- 1a) Groups: $(3.5y, y, -5y)$; $(4x^3 y^{2/3}, 9x^3 y^{2/3})$; $-0.5x^2 y$; $(3/4) x y^{3/4}$
- 1b) Result: $2x^2 y - x + 5$
- 2a) $P = 5x^2 + 2xy - 4$
- 2b) $P(1,-2) = -3$
- 3a) $ANMP$ is a parallelogram
- 3b) $M$ positioned for $ANMP$ to be a rhombus
- 3c) $ABC$ right isosceles, $M$ midpoint of $BC$ for $ANMP$ square