= (0.5x + y - 3z)(0.5x + y - 3z)= (0.5x)(0.5x) + (0.5x)(y) - (0.5x)(3z) + (y)(0.5x) + (y)(y) - (y)(3z) - (3z)(0.5x) - (3z)(y) + (3z)(3z)= 0.25x^2 + 0.5xy - 1.5xz + 0.5xy + y^2 - 3yz - 1.5xz - 3yz + 9z^2= 0.25x^2 + y^2 + 9z^2 + xy - 3xz - 3yz
= (0.5x + y - 3z)(0.5x + y - 3z)
= (0.5x)(0.5x) + (0.5x)(y) - (0.5x)(3z) + (y)(0.5x) + (y)(y) - (y)(3z) - (3z)(0.5x) - (3z)(y) + (3z)(3z)
= 0.25x^2 + 0.5xy - 1.5xz + 0.5xy + y^2 - 3yz - 1.5xz - 3yz + 9z^2
= 0.25x^2 + y^2 + 9z^2 + xy - 3xz - 3yz