Core Connections Integrated III, 2015
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Core Connections Integrated III, 2015 View details
1. Section 6.1
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Exercise 10 Page 271

Solve the equation resulting from equating f(x) and g(x). The solutions are the x-coordinates of the points of intersection.

(3, 10) and (1/2, 0 )

Practice makes perfect
We want to find the points at which the graphs of functions f(x) = 2x^2-3x+1 and g(x) = 4x-2 intersect. If x is an x-coordinate of the point of intersection, then f(x) = g(x). Therefore, we can set these functions equal to each other to write an equation for such values of x. f(x)&=g(x) 2x^2-3x+1&=4x-2 By doing so, we have written a quadratic equation for x. Now, let's transform it so that the right-hand side equals 0.
2x^2-3x+1 = 4x-2
2x^2-7x+1 = -2
2x^2-7x+3 = 0
Next, we will factor the polynomial on the left-hand side.
2x^2-7x+3 = 0
2x^2-6x - x+3 = 0
2x(x-3) - x+3 = 0
2x(x-3) - (x-3) = 0
(x-3)(2x-1) = 0
Now, by the Zero Product Property the resulting equation is satisfied if either of the two factor equals 0. (x-3)(2x-1) = 0 ⇕ x-3 = 0 or 2x-1 = 0 Let's solve the first of the resulting equations. x- 3 = 0 ⇔ x = 3 One of the solutions to our equation is x=3. Now, let's find the other solution by solving the second equation.
2x-1 = 0
2x=1
x = 1/2
The second solution to our equation is x = 12. The two solutions to our equation are also the x-coordinates of the points of intersection of our functions. To find the y-coordinates by substituting each solution for x in the equation for g(x), one solution at a time. We will start with x=3.
g(x) = 4x - 2
g( 3) = 4( 3)-2
g(3) = 12-2
g(3) = 10
Therefore, the first point of intersection has coordinates ( 3, 10). Now, let's substitute 12.
g(x) = 4x - 2
g( 1/2) = 4( 1/2)-2
g( 1/2 ) = 4/2-2
g( 1/2 ) = 2-2
g( 1/2 ) = 0
The second point of intersection has coordinates ( 12, 0).