X² - 12x + 36 = 0

Solutions?

Factors of 36 that add up to - 12

-6 and - 6

(x - 6) (x - 6)

Set them both to equal 0 and solve for x

x - 6 = 0

x - 6 = 0

x = 6

x = 6

X² - 12x + 36 = 0

We know this is in standard form so we can use the quadratic formula. Indeed like a previous solution posted you can use factors, that is quicker but this will always work so let's see.

Now let's fill the gaps in the formula

x = 12 + - square root of (144 - 4 (1) (36)) / 2

X = 12 + - square root of (144 - 144) / 2

X = 12 / 2

X = 6