Example

Factoring 4x2+12x+94x^2 + 12x + 9

Factor the trinomial 4x2+12x+94x^2 + 12x + 9 by applying the perfect square trinomials pattern.

Step 1: Check if the trinomial fits the perfect square pattern a2+2ab+b2a^2 + 2ab + b^2.

  • Is the first term a perfect square? Yes: 4x2=(2x)24x^2 = (2x)^2, so a=2xa = 2x.
  • Is the last term a perfect square? Yes: 9=329 = 3^2, so b=3b = 3.
  • Is the middle term 2ab2ab? Check: 22x3=12x2 \cdot 2x \cdot 3 = 12x. Yes, the middle term matches.

Step 2: Write the expression as the square of a binomial. Because the middle term is positive, use the pattern (a+b)2(a + b)^2: 4x2+12x+9=(2x+3)24x^2 + 12x + 9 = (2x + 3)^2

Step 3: Check by multiplying: (2x+3)2=(2x)2+2(2x)(3)+32=4x2+12x+9(2x + 3)^2 = (2x)^2 + 2(2x)(3) + 3^2 = 4x^2 + 12x + 9

The factored form is (2x+3)2(2x + 3)^2.

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Updated 2026-04-29

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