Pearson Algebra 2 Common Core, 2011
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Pearson Algebra 2 Common Core, 2011 View details
End-of-Course Assessment

Exercise 10 Page 965

Remember the Vertex Form of a quadratic function.

H

Practice makes perfect

We are asked to write an equation for the parabola that has its axis of symmetry at x= - 3. Also, we know that its range includes all real numbers less than or equal to 4. This means that the parabola faces downward and its absolute maximum point goes to 4. Let's see its graph!

As we can see from the graph, the vertex of this parabola lies at ( - 3, 4). By knowing these, we can use the Vertex Form of a quadratic function to write our equation. Let's remember it! y = a(x- h)^2+ k In this form a gives the direction of the parabola. When a>0 the parabola faces upward and when a<0 it faces downward. Moreover, ( h, k) represents the vertex of the parabola. Knowing this, let's substitute h= -3 and k= 4 into the above equation. y = a(x-( - 3))^2+ 4 ⇓ y = a(x+3)^2+4 Great! Now, we can eliminate the options F and G because they have different vertices. Next, let's consider the value of a. Since we know that our function opens downward, the value of a must be negative. Therefore, we can conclude that our only possible answer would be option H in the case of a= -1. y = -(x+3)^2+4