Core Connections Integrated II, 2015
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Core Connections Integrated II, 2015 View details
4. Section 9.4
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Exercise 140 Page 532

Practice makes perfect
a Examining the system, we notice that both equations have y isolated. Therefore, we can solve this system by using the Substitution Method.
x^2-4x+5 = - x^2+4x-1 Let's solve this equation by using the Quadratic Formula. Before we can do that though, we must move all terms to one side of the equation.
x^2-4x+5 = - x^2+4x-1
Simplify
2x^2-4x+5 =4x-1
2x^2-8x+5 =-1
2x^2-8x+6 =0
x^2-4x+3 =0
Now we can solve the equation using the Quadratic formula.
x^2-4x+3=0
x=-( -4) ± sqrt(( -4)^2-4( 1)( 3))/2 * 1
Simplify right-hand side
x=4± sqrt((-4)^2-4(1)( 3))/2 * 1
x=4± sqrt(16-12)/2
x=4 ± sqrt(4)/2
x=4 ± 2/2
x=2 ± 1
lcx=2-1 & (I) x=2+1 & (II)

(I), (II): Add and subtract terms

lx_1=1 x_2=3
The system has two solutions, one at x=1 and another at x=3. This means the functions intersect twice. By substituting these values into either equation, we can calculate the corresponding y-values. y= 1^2-4( 1)+5 ⇔ y=2 y= 3^2-4( 3)+5 ⇔ y=2 The system has two points of intersection, (1,2) and (3,2).
b Like in Part A, we will use the Substitution Method to solve this system.
x^2-x-2 =x^2+2x+1
Simplify
- x-2 =2x+1
- 3x-2 =1
- 3x=3
x=-1
As we can see, we did not need to use the Quadratic Formula to solve the equation. The system has a solution in x=-1. By substituting this value into either equation, we can calculate the corresponding y-value. y=( -1)^2-( -1)-2 ⇔ y=0 The system has a point of intersection at (-1,0).