Q. Rewrite the equation by completing the square.x2+10x+21=0(x+□)2=□
Rewrite equation in form: Rewrite the equation in the form of x2+bx=c.Subtract 21 from both sides to set the equation up for completing the square.x2+10x+21−21=0−21x2+10x=−21
Subtract to set up: Find the number to complete the square.To complete the square, we need to add (2b)2 to both sides of the equation, where b is the coefficient of x.In this case, b=10, so (210)2=(5)2=25.
Find number to complete: Add 25 to both sides of the equation to complete the square.x2+10x+25=−21+25x2+10x+25=4
Add to complete square: Factor the left side of the equation.The left side of the equation is now a perfect square trinomial, so it can be factored into (x+5)2.(x+5)2=4
Factor left side of equation: Write the completed square form of the equation.The equation in completed square form is (x+5)2=4.
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