[tex] {(a - b)}^{2} = {a}^{2} - 2ab + {b }^{2} \\ (a + b)(a - b) = {a}^{2} - {b}^{2} \\ e(x) = {x}^{2} - 2 \times 3 \times x + {3}^{2} - 3x + 30 - {x}^{2} + {4}^{2} \\ e(x) = {x}^{2} - 6x + 9 - 3x + 30 - {x}^{2} + 16 \\ e(x) = - 9x + 55[/tex]
E(n) >=1
-9n+55>=1
-9n>=1-55
-9n>=-54
n<=-54:(-9)
n<=6
n€{1, 2, 3, 4, 5, 6}
