McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
5. Solving Quadratic Equations by Using the Quadratic Formula
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Exercise 27 Page 137

Make sure you write all the terms on the left-hand side of the equation and simplify as much as possible before using the Quadratic Formula.

3

Practice makes perfect
We will use the Quadratic Formula to solve the given quadratic equation. ax^2+ bx+ c=0 ⇕ x=- b± sqrt(b^2-4 a c)/2 a Let's start by rewriting the equation so all of the terms are on the left-hand side and then simplify as much as possible.
2x^2 = 12x - 18
2x^2 - 12x = - 18
2x^2 - 12x + 18 = 0
2(x^2 - 6x + 9) = 0
x^2 - 6x + 9 = 0
Now, we can identify the values of a, b, and c. x^2 - 6x + 9 = 0 ⇕ 1x^2+( - 6)x+ 9=0 We see that a= 1, b= - 6, and c= 9. Let's substitute these values into the Quadratic Formula.
x=- b±sqrt(b^2-4ac)/2a
x=- ( -6)±sqrt(( - 6)^2-4( 1)( 9))/2( 1)
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Solve for x and Simplify
x=6±sqrt((- 6)^2-4(1)(9))/2(1)
x=6±sqrt(36-4(1)(9))/2(1)
x=6±sqrt(36-36)/2
x=6±sqrt(0)/2
x=6± 0/2
Since adding or subtracting zero does not change the value of a number, the numerator will simplify to 6. Therefore, we will get only one value of x. x = 6/2 ⇔ x = 3 Using the Quadratic Formula, we found that the solution of the given equation is x = 3.