McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
5. Quadratic Inequalities
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Exercise 70 Page 213

Practice makes perfect
a We want to use the discriminant of the given quadratic equation to determine the number and type of solutions. In the Quadratic Formula, b^2-4ac is the discriminant.
ax^2+bx+c=0 ⇔ x=- b±sqrt(b^2-4ac)/2aIf we just want to know the number of solutions, and not the solutions themselves, we only need to work with the discriminant. Since the given equation is in standard form, we can identify the values of a, b, and c. 4x^2+7x-3=0 ⇔ 4x^2+ 7x+( - 3)=0 Finally, let's evaluate the discriminant.
b^2-4ac
7^2-4( 4)( - 3)
â–Ľ
Simplify
49-4(4)(- 3)
49-4(- 12)
49+48
97
The discriminant is 97.
b Since the discriminant is 97, greater than zero, the quadratic equation has two real roots.

Extra

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.