MHB Intersection points of two quadratic functions

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The discussion focuses on finding the intersection points of the quadratic functions f(x) = 2x² - 8x and g(x) = x² - 3x + 6. Graphical representation shows that the functions intersect at the points (-1, 10) and (6, 24). A table of values confirms these intersections by showing equal outputs for both functions at the specified x-values. Algebraic verification involves setting f(x) equal to g(x), leading to the quadratic equation x² - 5x - 6 = 0, which factors to (x + 1)(x - 6) = 0. The solutions x = -1 and x = 6 correspond to the intersection points, confirming the findings through multiple representations.
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Justify the following by using table, graph and equation. use words to explain each representation
f(X) = 2 x2 - 8x and g(x) = x2-3x+ 6 the points (-1,10) and (6,24)
 
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Hello, and welcome to MHB! (Wave)

Let's first look at a graph of the two given functions and the given points:

View attachment 8479

From the graph, it appears the given points are where the two functions \(f\) and \(g\) intersect. Let's look at a table:

[table="width: 300, class: grid"]
[tr]
[td]\(x\)[/td]
[td]\(f(x)\)[/td]
[td]\(g(x)\)[/td]
[/tr]
[tr]
[td]-2[/td]
[td]24[/td]
[td]16[/td]
[/tr]
[tr]
[td]-1[/td]
[td]10[/td]
[td]10[/td]
[/tr]
[tr]
[td]0[/td]
[td]0[/td]
[td]6[/td]
[/tr]
[tr]
[td]1[/td]
[td]-6[/td]
[td]4[/td]
[/tr]
[tr]
[td]2[/td]
[td]-8[/td]
[td]4[/td]
[/tr]
[tr]
[td]3[/td]
[td]-6[/td]
[td]6[/td]
[/tr]
[tr]
[td]4[/td]
[td]0[/td]
[td]10[/td]
[/tr]
[tr]
[td]5[/td]
[td]10[/td]
[td]16[/td]
[/tr]
[tr]
[td]6[/td]
[td]24[/td]
[td]24[/td]
[/tr]
[tr]
[td]7[/td]
[td]42[/td]
[td]34[/td]
[/tr]
[/table]

The table would indicate that the two given points are where the two functions intersect. Now, we can verify this algebraically as follows:

$$f(x)=g(x)$$

$$2x^2-8x=x^2-3x+6$$

Collect everything on the LHS:

$$x^2-5x-6=0$$

Factor:

$$(x+1)(x-6)=0$$

And so the values of \(x\) for which the two functions are equal are:

$$x\in\{-1,6\}$$

Let's verify by finding the values of the functions for those two values of \(x\):

$$f(-1)=2(-1)^2-8(-1)=2+8=10$$

$$g(-1)=(-1)^2-3(-1)+6=1+3+6=10$$

$$f(6)=2(6)^2-8(6)=72-48=24$$

$$g(6)=(6)^2-3(6)+6=36-18+6=24$$

And so we may conclude that the functions:

$$f(x)=2x^2-8x$$ and $$g(x)=x^2-3x+6$$

intersect at the points:

$$(-1,10)$$ and $$(6,24)$$

Does all that make sense?
 

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Here is a little puzzle from the book 100 Geometric Games by Pierre Berloquin. The side of a small square is one meter long and the side of a larger square one and a half meters long. One vertex of the large square is at the center of the small square. The side of the large square cuts two sides of the small square into one- third parts and two-thirds parts. What is the area where the squares overlap?

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