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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 21 Page 137

Make sure you write all the terms on the left-hand side of the equation before using the Quadratic Formula.

- 1.2, - 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. 5x^2 + 21x = - 18 ⇕ 5x^2 + 21x + 18 = 0 Now, we can identify the values of a, b, and c. 5x^2+ 21x+ 18=0 We see that a= 5, b= 21, and c= 18. Let's substitute these values into the Quadratic Formula.

x=- b±sqrt(b^2-4ac)/2a

SubstituteValues

Substitute values

x=- 21±sqrt(( 21)^2-4( 5)( 18))/2( 5)

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Solve for x and Simplify

CalcPow

Calculate power

x=- 21±sqrt(441-4(5)(18))/2(5)

Multiply

x=- 21±sqrt(441-360)/10

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