Explicație pas cu pas:
a)
[tex]E(x) = {(2x + 1)}^{2} - {(x - 1)}^{2} + (x - 2)(x + 2) - 3 {x}^{2} + 14 = 4 {x}^{2} + 4x + 1 - {x}^{2} + 2x - 1 + {x}^{2} - 4 - 3 {x}^{2} + 14 = 5 {x}^{2} - 4 {x}^{2} + 6x + 15 - 5 = {x}^{2} + 6x + 10[/tex]
b)
[tex]E(-3) = {( - 3)}^{2} + 6( - 3)+ 10 = 9 - 18 + 10 = 19 - 18 = 1[/tex]
c)
[tex]E(a) = {a}^{2} + 6a + 10 = {a}^{2} + 6a + 9 + 1 = {(a + 3)}^{2} + 1 > 0[/tex]
