[tex](2.6w - 4.2x) + (1.3w + 8.1y)(1.3w + 8.1y) + (3.6y + 9.6x)(3.6y + 9.6x)\\= (2.6w - 4.2x) + (1.69w^2 + 10.53wy + 10.53wy + 65.61y^2) + (12.96y^2 + 34.56xy + 34.56xy + 92.16x^2)\\= 2.6w - 4.2x + 1.69w^2 + 21.06wy + 65.61y^2 + 12.96y^2 + 69.12xy + 92.16x^2\\= 2.6w - 4.2x + 1.69w^2 + 21.06wy + 78.57y^2 + 69.12xy + 92.16x^2[/tex]
