McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
6. The Quadratic Formula and the Discriminant
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Exercise 10 Page 269

Practice makes perfect
a In the Quadratic Formula, b^2-4ac is the discriminant.
ax^2+bx+c=0 ⇔ x=- b±sqrt(b^2-4ac)/2aSince the given equation is already in standard form, we can identify the values of a, b, and c. 3x^2+ 8x+ 2=0 Now, let's evaluate the discriminant.
b^2-4ac
8^2-4( 3)( 2)
Simplify
64-4(3)(2)
64-12(2)
64-24
40
The discriminant is 40.
b We want to use the discriminant of the given quadratic equation to determine the number and type of the roots. If we do not want to know the exact values of the roots, we only need to work with the discriminant. From Part A, we know that the discriminant of the given equation is 40.
Equation:& 3x^2+8x+2=0 Discriminant:& 40 Since the discriminant is greater than zero and not a perfect square, the quadratic equation has two irrational roots.

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Further information
If the discriminant is greater than zero, the equation will have two real solutions. If it is equal to zero, the equation will have one real solution. Finally, if the discriminant is less than zero, the equation will have no real solutions.