a)
[tex] {x}^{2} + x - 12 = {x}^{2} - 3x + 4x - 12 = x(x - 3) + 4(x - 3) = (x + 4)(x - 3)[/tex]
b)
[tex]E(x) = {(x - 1)}^{2} + (x + 4)(x - 3) - 2( {x}^{2} - 4) [/tex]
[tex]E(x) = {x}^{2} - 2 \times 1 \times x + {1}^{2} + {x}^{2} + x - 12 - 2 {x}^{2} + 8 [/tex]
[tex]E(x) = - 2 x + {1}^{} + x - 12 + 8 [/tex]
[tex]E(x) = - x - 3 [/tex]
