Question

How do you solve using the completing the square method `x^2 + 2x = 35`?

Answer 1

`x=5`
or
`x=-7`
(see below for solution by completing the squares)

Explanation:

Given `x^2+2x=35`

Complete the square:
`color(white)("XXX")x^2+2xcolor(red)(+1)=35color(red)(+1)`

Re-write as squared terms
`color(white)("XXX")(x+1)^2=6^2`

Take square root of both sides:
`color(white)("XXX")x+1=+-6`

`x=5 or x=-7`