Core Connections Algebra 2, 2013
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Core Connections Algebra 2, 2013 View details
1. Section 8.1
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Exercise 57 Page 388

Practice makes perfect
a We are given two x-intercepts of a quadratic polynomial. Since x-intercepts are the roots of a quadratic equation, we can write an equation in factored form. Then we will change it to standard form by multiplying the factors.
Factored Form:& y=a(x-p)(x-q) Standard Form:& y=ax^2+bx+c In the factored form p and q are the roots of the equation. Let's substitute 34 and -2 to partially write our equation. y=a(x- 3/4 )( x-(-2)) ⇕ y=a( x- 3/4 )(x+2) Since a does not have any effect on the roots, we can choose any value other than 0. In order to have integer coefficients, we will let a= 4. This will allow us to eliminate the fraction after we distribute. y= 4( x- 3/4 )(x+2) Finally, let's use the Distributive Property to obtain the standard form.
y=4( x- 3/4 )(x+2)
y=(4x-3)(x+2)
â–Ľ
Multiply parentheses
y=x(4x-3)+ 2(4x-3)
y=4x^2-3x+ 2(4x-3)
y=4x^2-3x+ 8x-6
y=4x^2+5x-6
Please note that this is just one example of a quadratic equation that satisfies the given requirements.
b Similarly as in Part A, we will first write the equation in factored form and then multiply the factors to obtain the standard form. Since we are told the x-intercepts are -sqrt(5) and sqrt(5), we can partially write the factored form of our equation.
y=a( x-( - sqrt(5)) ) ( x-sqrt(5) ) ⇕ y=a( x+ sqrt(5) ) ( x-sqrt(5) )We can choose any value of a except 0. For simplicity, we will let a= 1. y= 1( x+ sqrt(5) ) ( x-sqrt(5) ) ⇕ y=( x+ sqrt(5) ) ( x-sqrt(5) ) Finally, let's use the Distributive Property to obtain the standard form. Note that it is a product of conjugate binomials.
y=( x+ sqrt(5) ) ( x-sqrt(5) )
â–Ľ
Multiply parentheses
y=x^2-(sqrt(5))^2
y=x^2-5
Once again, please note that this is just one example of a quadratic equation that satisfies the given requirements.