Math Problem Statement

Select all the points of intersection between the graphs of the functions f(x)=(x+5)(x−2) and g(x)=(2x+1)(x−2).

Multiple select question. cross out

A) (−5,0)

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B) (−12,0)

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C) (−2,−12)

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D) (2,0)

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E) (4,18)

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F) (5,30)

Solution

To find the points of intersection between the graphs of the functions f(x)=(x+5)(x2)f(x) = (x+5)(x-2) and g(x)=(2x+1)(x2)g(x) = (2x+1)(x-2), we need to set the two functions equal to each other and solve for xx.

Step 1: Set the equations equal to each other.

(x+5)(x2)=(2x+1)(x2)(x+5)(x-2) = (2x+1)(x-2)

Since both sides contain (x2)(x-2), we can divide both sides of the equation by (x2)(x-2) as long as x2x \neq 2.

x+5=2x+1x+5 = 2x+1

Step 2: Solve for xx.

x+5=2x+1x+5 = 2x+1 Subtract xx from both sides: 5=x+15 = x+1 Subtract 1 from both sides: x=4x = 4

So, one point of intersection occurs when x=4x = 4.

Step 3: Find the corresponding yy-coordinate.

Substitute x=4x = 4 into either function to find the yy-value. Let's use f(x)f(x): f(4)=(4+5)(42)=9×2=18f(4) = (4+5)(4-2) = 9 \times 2 = 18 Thus, the point of intersection is (4,18)(4, 18).

Step 4: Check if x=2x = 2 is also a solution.

Since both functions have (x2)(x-2) as a factor, let's substitute x=2x = 2 into both functions: f(2)=(2+5)(22)=7×0=0f(2) = (2+5)(2-2) = 7 \times 0 = 0 g(2)=(2×2+1)(22)=5×0=0g(2) = (2 \times 2 + 1)(2-2) = 5 \times 0 = 0 Both functions give y=0y = 0 when x=2x = 2. Therefore, (2,0)(2, 0) is also a point of intersection.

Step 5: Conclusion

The points of intersection are (4,18)(4, 18) and (2,0)(2, 0).

The correct selections are:

  • D) (2,0)(2, 0)
  • E) (4,18)(4, 18)

Would you like more details on the calculations or further explanation?

Here are 5 related questions to explore:

  1. How do you factor quadratic equations like f(x)=(x+5)(x2)f(x) = (x+5)(x-2)?
  2. How would the points of intersection change if the functions were modified?
  3. What is the significance of dividing by (x2)(x-2) in this problem?
  4. Can there be cases where dividing by a common factor might lose valid solutions?
  5. How can you graphically verify the points of intersection?

Tip: Always check if common factors can affect the domain of your solution before dividing through them!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Intersection of Functions

Formulas

Factoring Quadratics: f(x) = (x+5)(x-2), g(x) = (2x+1)(x-2)
Solving for x by setting f(x) = g(x)

Theorems

Zero Product Property

Suitable Grade Level

Grades 9-10