Factor by using the perfect square trinomial formula

36x^2 + 12xy + Y^2

^= equals the power of..

36x^2 + 12xy + y^2
= (6x)^2 + 2(6xy) + (y)^2
Let a = 6x, b = y
(a)^2 + 2(ab) + (b)^2 = (a + b)^2
(6x)^2 + 2(6xy) + (y)^2
= (6x + y)^2

36x² + 12xy + y² is in the form a² + 2ab + b²

it factors into the form (a + b)²

If a² is 36x².....then a = 6x
If b² is y²......then b = y

= (6x + y)² {factored by substituting 6x in for a and y in for b, into (a + b)²}

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