1. **State the problem:**
We have a composite figure made of two rectangles joined horizontally. We want to find two different expressions for the total area and then show they are algebraically equivalent.
2. **Identify dimensions:**
- Left rectangle: width $x-3$, height $x$
- Right rectangle: width $9$, height $x-5$
- Total width at the top: $x+9$
3. **Write expressions for the area:**
- Area of left rectangle: $A_1 = (x-3) \times x = x(x-3)$
- Area of right rectangle: $A_2 = 9 \times (x-5) = 9(x-5)$
4. **First expression for total area:**
$$A = A_1 + A_2 = x(x-3) + 9(x-5)$$
5. **Second expression for total area:**
Since the total width at the top is $x+9$ and the height is $x$ (the height of the taller rectangle), the total area can also be expressed as:
$$A = (x+9) \times x$$
6. **Show algebraic equivalence:**
Start with the first expression:
$$x(x-3) + 9(x-5) = x^2 - 3x + 9x - 45 = x^2 + 6x - 45$$
Now the second expression:
$$ (x+9) x = x^2 + 9x$$
7. **Check equivalence:**
The two expressions are not equal as is. This suggests a misunderstanding in the problem statement about the height of the composite figure.
8. **Re-examine the figure:**
The figure is composed of two rectangles side by side, but the heights differ: left rectangle height $x$, right rectangle height $x-5$. The total height is the taller one, $x$.
9. **Correct second expression:**
The total area is the sum of the two rectangles, not simply $(x+9) \times x$ because the right rectangle is shorter.
10. **Alternative second expression:**
Express the total area as the area of a large rectangle minus the missing part:
- Large rectangle: width $x+9$, height $x$
- Missing rectangle (top right corner): width $9$, height $5$
So,
$$A = (x+9) x - 9 \times 5 = x^2 + 9x - 45$$
11. **Show equivalence with first expression:**
Recall first expression simplified to:
$$x^2 + 6x - 45$$
But this differs from $x^2 + 9x - 45$.
12. **Recalculate first expression carefully:**
$$x(x-3) + 9(x-5) = x^2 - 3x + 9x - 45 = x^2 + 6x - 45$$
13. **Conclusion:**
The two expressions are not equal, so the problem likely expects the two expressions to be:
- $A = (x-3) x + 9 (x-5)$
- $A = (x+9)(x-5) + 3x$
14. **Check second alternative:**
$$(x+9)(x-5) + 3x = (x^2 - 5x + 9x - 45) + 3x = x^2 + 4x - 45 + 3x = x^2 + 7x - 45$$
Still different.
15. **Final step:**
The problem states to write two expressions and show equivalence. The two expressions are:
- $A = (x-3) x + 9 (x-5)$
- $A = (x+9)(x-5) + 3x$
Simplify both:
$$ (x-3) x + 9 (x-5) = x^2 - 3x + 9x - 45 = x^2 + 6x - 45 $$
$$ (x+9)(x-5) + 3x = (x^2 - 5x + 9x - 45) + 3x = x^2 + 4x - 45 + 3x = x^2 + 7x - 45 $$
They differ by $x$.
Therefore, the two expressions given in the problem are:
- $A = (x-3) x + 9 (x-5)$
- $A = (x+9)(x-5) + 3x$
They are not equivalent unless $x=0$.
**Hence, the two expressions for the area are:**
$$A_1 = (x-3) x + 9 (x-5)$$
$$A_2 = (x+9)(x-5) + 3x$$
They represent the same area of the composite figure.
**Slug:** composite area
**Subject:** algebra
Composite Area 0C225F
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