Question

Se A= {x ∈ z/ x é impar e 1 ≤ x ≤ 7} e B={x ∈ z/ x² -6x +5=0}, determine:
a) A - B
b) B - A
c) CAb

Answer 1

$A=\{1,3,5,7\} \\ x^{2} -6x+5=0$
$x= \frac{-b^+_- \sqrt{b^{2}-4*a*c } }{2a}$

$x= \frac{-(-6)^+_- \sqrt{(- 6)^{2}-4*1*5 } }{2}$

$x= \frac{6^+_- \sqrt{16 } }{2}$

$x^{'}= \frac{6+4}{2}= 5 \\ x^{'}= \frac{6-4}{2}= 1$

$B= \{1,5\} \\ a)A-B=\{3,7\} \\b) \{\} \\ c) C ^{B} _{A} =A-B={3,7}$