McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
2. Solving Quadratic Equations by Graphing
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Exercise 44 Page 109

Practice makes perfect
a A double root occurs when the quadratic equation is a perfect square trinomial. Let x=2 be the double root of our quadratic equation. With this, we can write the equation as shown below.
(x-2)(x-2)=0 ⇔ (x-2)^2=0 Now, to write the above equation in standard form, we can simplify the left-hand side.
(x-2)^2=0
x^2-2(x)(2)+2^2=0
x^2-4x+2^2=0
x^2-4x+4=0
b Let x= 12 be the rational root and x=3 be the integer root. With this, we can write the equation shown below.
(x-1/2)(x-3)=0 Let's apply the Distributive Property to simplify the left-hand side of the above equation.
(x-1/2)(x-3)=0
x(x-3)-1/2(x-3)=0
x^2-3x-1/2(x-3)=0
x^2-3x-1/2x+3/2=0
2x^2-6x-x+3=0
2x^2-7x+3=0
c If a quadratic equation has two distinct integer roots that are additive opposites, then they add up to 0. Let's assume x=4 and x=-4 are the roots of the quadratic equation. From here, we can write the quadratic equation as follows.
(x-4)(x+4)=0 Now, we will apply the Distributive Property to simplify the left-hand side.
(x-4)(x+4)=0
x(x+4)-4(x+4)=0
x^2+4x-4(x+4)=0
x^2+4x-4x-16=0
x^2-16=0
The left-hand side of the above equation is called the Difference of Two Squares.