The sale tax is $45 on the purchase of a dining room set for $1125. Find the sales tax rate?
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Answer:
Step-by-step explanation:
Vertex form of a quadratic equation;
Vertex of the parabolas (h, k)
The vertex of the parabola is either the minimum or maximum of the parabola. The axis of symmetry goes through the x-coordinate of the vertex, hence h = -3. The minimum of the parabola is the y-coordinate of the vertex, so k= 7. Now substitute it into the formula;
Now substitute in the given point; ( -1, 9) and solve for a;
Hence the equation in vertex form is;
In standard form it is;