Factor: 4x^4 + 19x^2 + 12

(4x^2+3)(x^2+4)

4x^4 + 19x^2 + 12
= 4x^4 + 16x^2 + 3x^2 + 12
= 4x^2(x^2 + 4) + 3(x^2 + 4)
= (4x^2 + 3)(x^2 + 4)

4(x²)² + 19x² + 12
4(x²)² + 16x² + 3x² +12
4x² (x² + 4) +3 (x² + 4)
(x² + 4) (4x² +3)

(4 + x2)(3 + 4x2)

256 + 38 +12
= 306