Q. A parabola graphed in the xy-plane has equation y=2x2−5x−3. What is the x-coordinate of the vertex of the parabola?
Identify quadratic equation: Identify the given quadratic equation.The given quadratic equation is y=2x2−5x−3.
Convert to vertex form: Convert the quadratic equation into vertex form.The vertex form of a quadratic equation is y=a(x−h)2+k, where (h,k) is the vertex of the parabola.To convert the given equation into vertex form, we need to complete the square.
Factor out x2 coefficient: Factor out the coefficient of x2 from the x terms.The coefficient of x2 is 2. We factor out 2 from the x terms to get:y=2(x2−(5/2)x)−3
Find (b/2)2: Find the value of (b/2)2 to complete the square.The coefficient of x is −5/2. We need to find (−5/4)2 to complete the square.(−5/4)2=(25/16)
Add and subtract (b/2)2: Add and subtract (b/2)2 inside the parentheses and simplify.y=2(x2−25x+1625)−2∗1625−3y=2(x−45)2−1650−3y=2(x−45)2−1650−1648y=2(x−45)2−1698
Identify vertex x-coordinate: Identify the x-coordinate of the vertex. The x-coordinate of the vertex is the value of h in the vertex form y=a(x−h)2+k. From the equation y=2(x−45)2−(1698), we can see that h=45.
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