Q. Complete the square to re-write the quadratic function in vertex form:y=x2−x−1Answer: y=
Identify Coefficients: Identify the coefficients of x2 and x in the quadratic function.The coefficient of x2 is 1, and the coefficient of x is −1. We will use these to complete the square.
Divide and Square: Divide the coefficient of x by 2 and square the result to find the value to add and subtract to complete the square.The coefficient of x is −1, so we divide it by 2 to get −21, and then square it to get (21)2=41.
Add/Subtract to Complete: Add and subtract the value found in Step 2 inside the function.We add and subtract 41 inside the function to complete the square.y=x2−x+41−41−1
Group and Combine: Group the terms to form a perfect square trinomial and combine the constants.y=(x2−x+41)−41−1y=(x−21)2−41−1
Combine Constants: Combine the constants to simplify the equation.We combine −41 and −1, which is the same as −41−44, to get −45.y=(x−21)2−45
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