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Rewrite the equation by completing the square.

{:[x^(2)+4x-21=0],[(x+◻)^(2)=◻]:}

Rewrite the equation by completing the square.\newlinex2+4x21=0x^2+4x-21=0\newline(x+)2=(x+\square)^2=\square

Full solution

Q. Rewrite the equation by completing the square.\newlinex2+4x21=0x^2+4x-21=0\newline(x+)2=(x+\square)^2=\square
  1. Rewrite equation: Rewrite the equation in the form of x2+bx=cx^2 + bx = c.\newlineWe start with the equation x2+4x21=0x^2 + 4x - 21 = 0 and add 2121 to both sides to isolate the x2x^2 and xx terms on one side.\newlinex2+4x21+21=0+21x^2 + 4x - 21 + 21 = 0 + 21\newlinex2+4x=21x^2 + 4x = 21
  2. Isolate x2x^2 and xx terms: Find the number to complete the square.\newlineTo complete the square, we need to add (b/2)2(b/2)^2 to both sides of the equation, where bb is the coefficient of xx. In this case, b=4b = 4.\newline(4/2)2=(2)2=4(4/2)^2 = (2)^2 = 4\newlineWe add 44 to both sides of the equation.\newlinex2+4x+4=21+4x^2 + 4x + 4 = 21 + 4\newlinex2+4x+4=25x^2 + 4x + 4 = 25
  3. Find completing the square number: Factor the left side of the equation.\newlineThe left side of the equation is now a perfect square trinomial, which can be factored into (x+2)2(x + 2)^2.\newline(x+2)2=25(x + 2)^2 = 25
  4. Factor left side of equation: Write the completed square form of the equation.\newlineThe completed square form of the equation is (x+2)2=25(x + 2)^2 = 25.

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