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Solve the equation using the Complete The Square Methodx^2+12x=13Do your work on paper. Take a picture, and upload it here. Show all your work/steps.

Solve the equation using the Complete The Square Methodx^2+12x=13Do your work on paper-example-1
User Zahid Karim
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1 Answer

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20 votes

Given the quadratic equation:


x^2+12x=13

We can rewrite the equation as follows:


\begin{gathered} x^2+12x-13=0 \\ x^2+2\cdot6\cdot x-13=0 \\ x^2+2\cdot6\cdot x+6^2-6^2-13=0 \\ (x^2+2\cdot6\cdot x+6^2)-36-13=0 \end{gathered}

We see that the term inside the parenthesis is a perfect square polynomial. Then:


(x+6)^2-49=0

Solving for x:


(x+6)^2=49

Taking the square on both sides:


\begin{gathered} √((x+6)^2)=√(49) \\ \\ |x+6|=7 \end{gathered}

This equation can turn into two equations:


\begin{gathered} x+6=7...(1) \\ x+6=-7...(2) \end{gathered}

Solving (1):


\begin{gathered} x=7-6 \\ \\ \Rightarrow x=1 \end{gathered}

Solving (2):


\begin{gathered} x=-7-6 \\ \\ \Rightarrow x=-13 \end{gathered}

Finally, the solutions to the equation are:


\begin{gathered} x_1=1 \\ \\ x_2=-13 \end{gathered}

User Anas Bakro
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