How do you complete the square?

Completing the square is often useful when solving equations! An example: x² +6x-7=0. Step 1) We want to move the constant to the right hand side: x²+6x=7. Step 2) Now, add the square of the coefficient of x on to both sides: x²+6x+3²=7+3² -> x²+6x+9=16. Step 3) Factorise the left hand side: (x+3)²=16. Step 4) Square root the equation and solve: x+3=+/-4  -> x=-3+/-4.