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Rewrite the function by completing the square.

{:[f(x)=x^(2)-16 x-100],[f(x)=(x+◻)^(2)+◻]:}

Rewrite the function by completing the square.\newlinef(x)=x216x100 f(x) = x^2 - 16x - 100 \newlinef(x)=(x+)2+ f(x) = (x + \square)^2 + \square

Full solution

Q. Rewrite the function by completing the square.\newlinef(x)=x216x100 f(x) = x^2 - 16x - 100 \newlinef(x)=(x+)2+ f(x) = (x + \square)^2 + \square
  1. Given quadratic function: We start with the given quadratic function:\newlinef(x) = x216x100x^2 - 16x - 100\newlineOur goal is to rewrite this function in the form of (x+a)2+b(x + a)^2 + b.
  2. Completing the square: To complete the square, we need to find a value that, when added and subtracted to the x216xx^2 - 16x part, completes the square. This value is found by taking half of the coefficient of xx, squaring it, and then adding it to both sides.\newlineThe coefficient of xx is 16-16, so half of 16-16 is 8-8, and (8)2=64(-8)^2 = 64.
  3. Adding and subtracting: We add and subtract 6464 to the function to complete the square:\newlinef(x)=x216x+6464100f(x) = x^2 - 16x + 64 - 64 - 100\newlineNow we have a perfect square trinomial x216x+64x^2 - 16x + 64 and a constant 164-164.
  4. Factoring the perfect square trinomial: We factor the perfect square trinomial:\newlinef(x) = (x - 88)^22 - 164164\newlineNow the function is in the completed square form.
  5. Checking the work: We check our work by expanding (x8)2(x - 8)^2 to ensure it gives us back the original x216xx^2 - 16x term:\newline(x8)2=x216x+64(x - 8)^2 = x^2 - 16x + 64\newlineThis matches the x216x+64x^2 - 16x + 64 part of our function, so there is no math error.

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