A dentist's office and parking lot are on a rectangular piece of land. The area (in square meters) of the land is represented by x² + x - 30. a. Write a binomial that represents t... A dentist's office and parking lot are on a rectangular piece of land. The area (in square meters) of the land is represented by x² + x - 30. a. Write a binomial that represents the width of the land. b. Find the perimeter of the land when the length of the dentist's office is 20 meters.
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Understand the Problem
This question involves a rectangular piece of land with a dentist's office and parking lot. The area of the land is given by the quadratic expression x² + x - 30. The problem requires to find a binomial that represents the width of the land and also to calculate the perimeter when the length of the dentist's office is 20 meters.
Answer
a. $x-5$ b. $58$
Answer for screen readers
a. $x-5$ b. $58$
Steps to Solve
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Factor the quadratic expression representing the area The area of the rectangular piece of land is given by $x^2 + x - 30$. We need to factor this quadratic expression to find the binomials that represent the length and width of the land. We look for two numbers that multiply to -30 and add to 1. These numbers are 6 and -5. Therefore, the factored form is $(x+6)(x-5)$.
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Determine the width From the image we can see that the length is $x+6$. Therefore the width must be $x-5$.
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Find the value of x when the length is 20 meters We are given that the length of the dentist's office is 20 meters. Since the length of the whole land is represented by $x + 6$, we set $x + 6 = 20$ and solve for $x$. $x + 6 = 20$ $x = 20 - 6$ $x = 14$
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Calculate the width Now that we know $x = 14$, we can find the width by substituting $x$ into the expression for the width, which is $x - 5$. Width $= x - 5 = 14 - 5 = 9$ meters.
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Calculate the perimeter The perimeter of a rectangle is given by the formula $P = 2(l + w)$, where $l$ is the length and $w$ is the width. We have $l = 20$ meters and $w = 9$ meters. $P = 2(20 + 9) = 2(29) = 58$ meters.
a. $x-5$ b. $58$
More Information
The problem combines factoring quadratic expressions with geometric concepts like area and perimeter of a rectangle.
Tips
- Confusing the length and width after factoring the quadratic expression. It's important to compare the factored expressions with the given dimensions in the diagram.
- Forgetting to substitute the value of $x$ back into the expression for the width.
- Using the wrong formula for the perimeter of a rectangle.
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