McGraw Hill Integrated II, 2012
MH
McGraw Hill Integrated II, 2012 View details
5. Quadratic Inequalities
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Exercise 59 Page 212

The boundaries are given by the x-intercepts of the graph of the corresponding function.

No, see solution.

Practice makes perfect
Recall that the boundaries are given by the x-intercepts of the graph of the corresponding function. We can find them by finding the zeroes of the quadratic equations. Let's have a look at our inequalities. Inequality (I) Inequality (II) [0.8em] x^2+4x-12 ≤ 0 1/2x^2+2x-6 ≤ 0 [1.3em] Corresponding Functions [0.8em] y = x^2+4x-12 y = 1/2x^2+2x-6 [1.3em] Corresponding Equations [0.8em] x^2+4x-12 = 0 1/2x^2+2x-6 = 0 [1.3em]

Notice that if we multiply the corresponding equation of Inequality (II) by 2, we obtain the same equation as that corresponding to Inequality (I). ( 12x^2+2x-6 = 0)* 2 ⇓ x^2+4x-12 = 0

This means that they will have the same solutions, and therefore their corresponding functions will have the same x-intercepts. We can graph both functions to see this explicitly.

Therefore, the boundaries for both solution sets are the same.