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 2 Page 137

Be careful with the signs when substituting in the Quadratic Formula.

8 and 2

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 To do so, we first need to identify the values of a, b, and c. x^2-10x+16=0 ⇔ 1x^2+( - 10)x+ 16=0 We see that a= 1, b= - 10, and c= 16. Let's substitute these values into the Quadratic Formula. Be careful with the signs!
x=- b±sqrt(b^2-4ac)/2a
x=- ( -10)±sqrt(( - 10)^2-4( 1)( 16))/2( 1)
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Solve for x and Simplify
x=10±sqrt((- 10)^2-4(1)(16))/2(1)
x=10±sqrt(100-4(1)(16))/2(1)
x=10±sqrt(100-4(16))/2
x=10±sqrt(100-64)/2
x=10±sqrt(36)/2
x=10± 6/2
The solutions for this equation are x= 10± 62. Let's separate them into the positive and negative cases.
x=10± 6/2
x_1=10+ 6/2 x_2=10- 6/2
x_1=16/2 x_2=4/2
x_1=8 x_2=2

Using the Quadratic Formula, we found that the solutions of the given equation are x_1=8 and x_2=2.