4
x2 + 20x - 39 = 0: Add 61 giving: x2 + 20x + 100 = (x + 10)2
81. To complete the square, halve the coefficient of the x term (18/2 = 9) and add the square of this (92 = 81) to both sides: x2 + 18x = -13 ⇒ x2 + 18x + 81 = -13 + 81 ⇒ (x + 9)2 = 68
-17
The idea is to take half the linear part (12, in this case), then square it. The constant part must be equal to this result.
You must add 1
4
it is 121
You must add (17n + 144).
You must add 36 to complete the square on the left hand side.You must add 36 to complete the square on the left hand side.You must add 36 to complete the square on the left hand side.You must add 36 to complete the square on the left hand side.
You need to add -6
The constant term - the part without a variable - must be equal to the square of one half the linear term - the number in front of the "x". That is, it must be (12/2)2 = 36.
9
If: x^2 +18x = 29 Then completing the square: (x+9)^2 -81 = 29 or (x+9)^2 = 110
144
-3
x2 + 20x - 39 = 0: Add 61 giving: x2 + 20x + 100 = (x + 10)2